Synthesis of Ferrocenyl Diphosphine Ligands: Substitution of α-Methoxy or α-Dimethylamino Groups...

pubs.acs.org/OrganometallicsPublished on Web 11/09/2010r 2010 American Chemical Society

Organometallics 2010, 29, 6443–6458 6443

DOI: 10.1021/om100843u

Synthesis of Ferrocenyl Diphosphine Ligands: Substitution of r-Methoxy

or r-Dimethylamino Groups by Phosphines. Retention versus Inversion:

A Stereochemical Study

Raffael Schuecker and Walter Weissensteiner*

Institute of Organic Chemistry, University of Vienna, W€ahringer Strasse 38, 1090 Vienna, Austria

Kurt Mereiter

Institute of Chemical Technologies andAnalytics, ViennaUniversity of Technology, Getreidemarkt 9/164SC,A-1060 Vienna, Austria

Matthias Lotz and Felix Spindler

Solvias AG, Synthesis and Catalysis, P.O. Box, CH-4002 Basel, Switzerland

Received August 31, 2010

The stereochemical course of the exchange reaction of R-methoxy or R-dimethylamino groups byphosphines in acetic acid has been studied for ferrocene derivatives that have either a ferrocenylethylor a benzylferrocenyl backbone. The reaction proceeded with either retention or inversion ofconfiguration depending on the substrate stereoisomer used. The parameters that influence thestereochemical course of these reactions, such as relative configuration or substitution patterns, arediscussed.

Introduction

In a very recent paper Knochel, Lotz, and co-workersreported on the synthesis and application of a novel type offerrocenyl diphosphine ligand (Chart 1, 1).1 In rhodium-catalyzed asymmetric hydrogenations of two alkenes theseligands performed excellently and gave products with quan-titative conversion and with high enantiomeric excess (up to96% ee). From a structural point of view, these ligandsdiffer significantly from typical ferrocenyl diphosphinessuch as the Taniaphos- or Josiphos-type ligands2 (Chart 1).

On complexation to a metal such as rhodium or palladium,all of these ligands are expected to form chelate complexes.However, unlike in the cases of Taniaphos3 and Josiphos,4 in

Chart 1

*To whom correspondence should be addressed. E-mail: [email protected].(1) Lotz, M.; Schuecker, R.; Mereiter, K.; Knochel, P. Organo-

metallics 2010, doi om100830m.(2) (a) Ferrocenes: Ligands,Materials and Biomolecules; �St�epni�cka, P.,

Ed.; Wiley: Chichester, 2008; (b) Hayashi, T. Asymmetric Cross-CouplingReactions in Asymmetric Synthesis; Christmann, M.; Br€ase, S., Eds.;Wiley-VCH: Weinheim, 2008; pp 97-101. (c) Togni, A. Angew. Chem.,Int. Ed. Engl. 1996, 35, 1475–1477.(3) (a) Ireland, T.; Grossheimann, G.; Wieser-Jeunesse, C.; Knochel,

P. Angew. Chem., Int. Ed. 1999, 38, 3212–3215. (b) Ireland, T.; Tappe, K.;Grossheimann,G.; Knochel, P.Chem.Eur. J. 2002, 8, 843–852. (c) Lotz,M.;Polborn, K.; Knochel, P. Angew. Chem., Int. Ed. 2002, 41, 4708–4711. (d)Tappe, K.; Knochel, P. Tetrahedron: Asymmetry 2004, 15, 91–102.(e) Chen, W.; Roberts, S. M.; Whittall, J.; Steiner, A. Chem. Commun.2006, 2916–2918. (f) Fukuzawa, S. I.; Yamamoto, M.; Kikuchi, S. J. Org.Chem. 2007, 72, 1514–1517. (g) Fukuzawa, S. I.; Yamamoto, M.; Hosaka,M.; Kikuchi, S. Eur. J. Org. Chem. 2007, 5540–5545. (h) Pugin, B.;Thommen, M.; Spindler, F.; Lotz, M.; Kesselgruber, M.; Feng, X. Stud.Surf. Sci. Catal. 2007, 172, 125–128.(4) (a) Togni, A.; Breutel, C.; Schnyder, A.; Spindler, F.; Landert, H.;

Tijani, A. J. Am. Chem. Soc. 1994, 116, 4062–4068. (b) Blaser, H. U.;Brieden, W.; Pugin, B.; Spindler, F.; Studer, M.; Togni, A.Top. Catal. 2002,19, 3–16.

6444 Organometallics, Vol. 29, No. 23, 2010 Schuecker et al.

complexes of ligands of type 1 the ferrocene unit does nottake part in the chelate ring but acts as a sterically demandingsubstituent on that ring. Indeed, an X-ray diffraction studyof a palladium dichloride complex of ligand 1a, [PdCl2(1a)],

1

showed that the ferrocene unit is attached to the chelate ringin a pseudo-axial fashion with the Cp ring located in closeproximity to the palladium atom (Figure 1).On the basis of these structural data we questioned whether

further ligand tuning could be achieved by substituting theferrocene Cp ring at either of its ortho positions (Chart 1,derivatives 2 and 3; Figure 1) and how such derivatives couldbe synthesized. The unsubstituted ligands of type 1have beenreported to be accessible through a short reaction sequence.Starting from enantiopure alcohol (R)-4, ligands (R)-1 wereobtained in a three-step sequence, 4f 5f 6f 1 (Scheme 1,top), in which all steps proceed with retention of configura-tion at the stereogenic (benzylic) carbon. In principle, theanalogous ligands 2 and 3 should also be accessible in asimilar reaction sequence with the last step (the exchange ofthe methoxy group by a phosphino group) being the key step(Scheme 1, bottom). For example, provided that both dia-stereomers (R,RFc)-7 and (R,SFc)-7 could be synthesized andthe configuration was retained, the exchange of the methoxyby a phosphino group would lead to the final products(R,RFc)-2 and (R,SFc)-2.

In the synthesis of ferrocene derivatives the exchange offunctional groups at the pseudo-benzylic R-position is con-sidered to be a standard procedure that occurs with retentionof configuration in almost all cases.2 Selected examples aregiven in Scheme 2. In 1970 Ugi and co-workers5 pointed outthat on treatment with methyl iodide and sodium methoxidethe dimethylamino groupof bothdiastereomers (R,SFc)-9 and(S,SFc)-9 can be substituted by a methoxy group with fullretention of configuration at the respective stereogenic center(Scheme 2, reactions 1 and 25). This type of reaction wassubsequently extended to a number of different leavinggroups such as acetate (reactions 46 and 57), hydroxyl andmethoxy groups (reaction 68), and different nucleophiles suchas amines, phosphines, sulfides, and carbon nucleophiles.9

These reactions have been used extensively,10 particularly inthe synthesis of catalyst ligands, as exemplified by the synthe-sis of Josiphos-type ligand (R,SFc)-13 (reactions 3

4a and 46).The vast majority of such substitution reactions proceed

with retention of configuration, and only in very few caseshas at least partial inversion of configuration been observed.11

A particularly interesting example was recently reported byFukuzawa and co-workers.12 The dimethylamino group of(R,RFc)-18 was replaced by a methoxy group with cleaninversion of configuration at the stereogenic center to give(S,RFc)-19 as the product (Scheme 3). This example isparticularly striking because substitution reactions on the

Figure 1. Molecular structure of [PdCl2(R)-1a] (adopted fromref 1).

Scheme 1. Synthesis of Ligands 1 (top) and Proposed Key Steps for the Synthesis of Ligands 2 and 3 (bottom)

(5) Marquarding, D.; Klusacek, H.; Gokel, G.; Hoffmann, P.; Ugi, I.J. Am. Chem. Soc. 1970, 92, 5389–5393.

(6) Hayashi, T.; Mise, T.; Fukushima, M.; Kagotani, M.; Nagashima,N.;Hamada,Y.;Matsumoto,A.;Kawakami, S.;Konishi,M.;Yamamoto,K.; Kumada, M. Bull. Chem. Soc. Jpn. 1980, 3, 1138–1151.

(7) Taylor, C. J.; Roca, F. X.; Richards, C. J. Synlett 2005, 2159–2162.(8) (a) Lotz, M.; Ireland, T.; Tappe, K.; Knochel, P. Chirality 2000,

12, 389–395. (b) Kl€otzing, R. J.; Lotz, M.; Knochel, P. Tetrahedron:Asymmetry 2003, 14, 255–264.

(9) (a) Array�as, R. G.; Adrio, J.; Carretero, J. C. Angew. Chem., Int.Ed. 2006, 45, 7674–7715. (b) Cabrera, S.; Mancheno, O. G.; Arrayas, R. G.;Alonso, I.; Mauleon, P.; Carretero, J. C. Pure Appl. Chem. 2006, 78, 257–265. (c) Barbaro, P.; Bianchini, C.; Giambastiani, G.; Parisel, S. L. Coord.Chem. Rev. 2004, 248, 2131–2150. (d) Atkinson, R. C. J.; Gibson, V. C.;Long, N. J. Chem. Soc. Rev. 2004, 33, 313–328.

(10) Blaser,H.U.;Chen,W.;Camponovo,F.;Togni,A.Chiral 1,2-disub-stituted ferrocenediphosphines for asymmetric catalysis in ref , pp 205-235.

(11) (a) Taniguchi,N.;Uemura,M.Tetrahedron Lett. 1998, 39, 5385–5388. (b) Burckhardt, U.; Drommi, D.; Togni, A. Inorg. Chim. Acta 1999,296, 183–194. (c) Fukuzawa, S.; Wachi, D.; Suzuki, T.; Itoh, S. J. Org.Chem. 2004, 69, 4991–4996.

(12) Fukuzawa, S. I.; Yamamoto, M.; Kikuchi, S. J. Org. Chem.2007, 72, 1514–1517.

Article Organometallics, Vol. 29, No. 23, 2010 6445

structurally related substrates (R)-61 (Scheme1) and (R,RFc)-168

(Scheme 2, reaction 6);both ofwhich contain a benzylferro-cenyl backbone;gave products (R)-1 and (R,RFc)-17 withclean retention of configuration. In view of these results, andparticularly since in the last step of the synthesis of ligands 2and 3 the nucleophilic exchange of a methoxy for a phos-phino unit is proposed, it seemed advantageous to study suchreactions in a more systematic way.In this contribution we report on the stereochemical course

of the exchange of R-methoxy by R-phosphino groups.

In addition, in order to synthesize Josiphos-type ligandswith(R,RFc) or (S,SFc) instead of the usual (S,RFc) or (R,SFc)configuration, the exchange of dimethylamino by phosphinogroups was also explored further.

Results

In order to investigate the stereochemical course of themethoxy/phosphino exchange reaction, the diastereomericpairs of 7 and 20-22, all of which have a benzylferrocenylbackbone, were synthesized in their racemic form and weresubjected to a reaction with diphenylphosphine in aceticacid. In addition, (S,SFc)-8 and (R,RFc)-11 were preparedin enantiomerically pure form and were reacted with dif-ferent secondary phosphines in acetic acid as the solvent(Chart 2). These reaction conditions were originally inventedfor the diastereoselective and high-yielding synthesis ofJosiphos-type ligands4a (Scheme 2, reaction 3).Synthesis of Derivatives 7, 8, 11, and 20-22. The amino

phosphine derivative (R,RFc)-11 was prepared according toa literature procedure.6 The racemic derivatives 20-22 ofrelative (R,SFc) configuration were obtained according to asynthesis route described for the corresponding enantiopurederivativeswith the (R,SFc) absolute configuration

8a (Scheme 4,top). The synthesis of the diastereomers rac-(S,SFc)-20-22

started from bromoferrocene and is depicted in Scheme 4(bottom). Reaction of bromoferrocene 24 with lithium2,2,6,6-tetramethylpiperidide (LiTMP)13 and benzaldehyde

Chart 2Scheme 2

Scheme 3

(13) (a) Steurer, M.; Tiedl, K.; Wang, Y.; Weissensteiner, W. Chem.Commun. 2005, 4929–4931. (b) Steurer, M.; Wang, Y.; Mereiter, K.;Weissensteiner, W. Organometallics 2007, 26, 3850–3859. (c) Butler,I. R.; Drew, M. G. B.; Greenwell, C. H.; Lewis, E.; Plath, M.; M€ussig, S.;Szewczyk, J. Inorg. Chem. Commun. 1999, 2, 576–580. (d) Mongin, F.;Schlosser, M. Tetrahedron Lett. 1996, 37, 6551–6554.


gave both diastereomers of alcohol 25, with rac-(S,SFc)-25being the major isomer (89% yield, 72% de). Methylationwith sodium hydride and methyl iodide resulted in rac-(S,SFc)-20 (89%), and subsequent bromide/lithium exchangeand quenching with chlorodiphenylphosphine or chlorotri-methylsilane gave rac-(S,SFc)-21 (78%) and rac-(S,SFc)-22(95%), respectively. The configurational assignment of allderivatives 20-22 is based on an X-ray diffraction study on(R,SFc)-21

8a as well as on NMR data.Both diastereomers of 7 are accessible in racemic form

from 2-ethylbromoferrocene,14 rac-26 (Scheme 5). Bromide/lithium exchange and subsequent reaction with 2-bromo-benzaldehyde led to both diastereomers of 27 in a ratio ofabout 1:1 and 79%overall yield. Furthermore, rac-(S,RFc)-27could be synthesized diastereoselectively by applying a pro-tocol originally developed by Richards and co-workers.7

Once again rac-26was used as the startingmaterial to obtain2-ethylferrocenecarbaldehyde, rac-28, in 93%yield, and sub-sequent treatment with 2-bromophenylmagnesium chlo-ride15 resulted in only one diastereomer for which;basedonRichards’ protocol7;the (S,RFc) relative configuration isexpected. After chromatographic separation the two diaste-reomers, rac-(R,RFc)-27 and rac-(S,RFc)-27, were methylated

with NaH/MeI to give the intermediates rac-(R,RFc)-29(66%) and rac-(S,RFc)-29 (69%). Further treatment withbutyllithium and chlorodiphenylphosphine gave the desiredproducts rac-(R,RFc)-7 (57%) and rac-(S,RFc)-7 (54%). Inthis case, the configurational assignment was achieved bycarrying out an X-ray diffraction study on one diastereomerof 7 (Figure 2), and this diastereomer was found to have the(S,RFc) relative configuration. The diastereomer of 7 used inthis study was that obtained from 27 in the reaction sequence27 f 29 f 7 and which itself was prepared diastereoselec-tively by Richards’ protocol. It is worth mentioning that theobserved (S,RFc) relative configuration of 7 is identical tothat expected for 27, and this suggests that, as in the sequence4 f 5 f 6 (Scheme 1), retention of configuration can beassumed for the sequence 27 f 29 f 7.

The enantiomerically pure trimethylsilyl-substituted deriv-ative (S,SFc)-8 was obtained in a three-step sequence from2-(trimethylsilyl)ferrocenecarbaldehyde, (SFc)-30 (Scheme 6).Once again, Richards’ protocol was followed, and aldehyde(SFc)-30 was reacted with 2-bromophenylmagnesium chlo-ride to give only one diastereomer of 31 (60% yield, afterrecrystallization from heptane >99.8% ee). An X-ray dif-fraction study on a racemic sample proved the expected(S,SFc) relative configuration of 31 (Figure 2). Methylationwith NaH/MeI gave intermediate (S,SFc)-32, which wasfinally transformed by treatment with nBuLi and ClPPh2into the desired product (S,SFc)-8.

Scheme 4

Scheme 5

(14) Zirakzadeh, A.; Schuecker, R.; Weissensteiner, W. Tetrahedron:Asymmetry 2010, 21, 1494–1502.(15) Krasovskiy, A.; Knochel, P. Angew. Chem., Int. Ed. 2004, 43,

3333–3336.


Methoxy/PhosphinoandDimethylamino/PhosphinoExchange.

All methoxy dervatives 7, 8, and 20-22 as well as aminoderivative 11 were reacted in acetic acid with diphenylphos-phine and in the cases of 8 and 11 also with other secondaryphosphines (for details see Scheme 7). The reaction mixtureswere analyzed, and the configurations of the products weredetermined. The results are summarized in Table 1.

When the R-methoxy-substituted derivatives 20-22 werereacted with HPPh2 in acetic acid, either one or two diastereo-meric products were obtained depending on the diastereomerused. The diastereomers of 20-22 with the (R,SFc) relative con-figuration in eachcasegaveonlyoneproductwithclean retentionof configuration and with quantitative conversion. In the case ofderivatives 20-22 with the relative (S,SFc) configuration, the

exchange reactionwas somewhat slower, and two products wereformed. For example, reaction of rac-(S,SFc)-20 with diphenyl-phosphine in acetic acid gave both diastereomers rac-(S,SFc)-33and rac-(R,SFc)-33, with rac-(S,SFc)-33 being the major diaste-reomer. In the case of the trihydridoboron complex of the rac-(S,SFc)-configured diastereomer the molecular structure wasdetermined by X-ray diffraction (Figure 2). Furthermore, prod-ucts 34 and 35;obtained as single diastereomers in the reactionof rac-(R,SFc)-21 and rac-(R,SFc)-22with HPPh2/AcOH;werereacted with BH3 3THF, and the NMR data of the resultingtrihydridoboron complexes rac-(R,SFc)-34(BH3) and rac-(R,SFc)-35(BH3) were found to be identical to those reportedin the literature,16 thus confirming the expected (R,SFc) relativeconfiguration.

Interestingly, although a wide variety of Josiphos-typeligands have been prepared with full retention of config-uration from (S,RFc)-11 [(S,RFc)-PPFA] or its enantiomer(R,SFc)-11 (Scheme 2, reaction 3), the synthesis of theirdiastereomeric analogues having (R,RFc) or (S,SFc) absoluteconfiguration has not yet been reported. For this purpose,and also since [(R,RFc)-PPFA] is structurally related to theR-methoxy-substituted derivative rac-(S,SFc)-21, (R,RFc)-11was reacted in acetic acid with the secondary phosphinesdiphenyl-, dicyclohexyl-, and di-tert-butylphosphine. Allthree phosphines reacted to give full conversion, and themajorproduct in each casewas thediastereomerwith retentionof configuration, i.e., (R,RFc)-36a-36c. However, unlike in thecase of rac-(S,SFc)-21 the reaction with diphenylphosphine andthe sterically more demanding dicyclohexylphosphine gave onlyone diastereomer, while with di-tert-butylphosphine both dia-stereomers were formed (de 84%).

Figure 2. Molecular structures of rac-(R,RFc)-2, rac-(S,RFc)-7, [PdCl2((R,SFc)-3b)], rac-(S,SFc)-31, and rac-(S,SFc)-33 in the solid state.

Scheme 6

(16) Ireland, T. Dissertation, Marburg, 1999.


In view of these results, we noticed with surprise that theR-methoxy/phosphino exchange reaction of derivatives 7

and 8with diphenylphosphine (7, 8) and bis(di-3,5-trifluoro-methylphenyl)phosphine (8) in certain cases proceeded withinversion of configuration. As reported recently, the at ferro-cene unsubstituted derivative (R)-6 reacts with HPPh2/AcOH with clean retention of configuration1 to give (R)-1ain 90% isolated yield and >99% de. Similarly, the at

ferrocene ethyl-substituted diastereomer rac-(R,RFc)-7 re-acted in a similar way to its structurally related compounds,but at phenyl unsubstituted analogues rac-(R,RFc)-20-22

and only one stereoisomer of 2 were formed with full con-version. An X-ray diffraction study revealed the (R,RFc)relative configuration (Figure 2), and this confirmed theclean retention of configuration for this substitution reac-tion. When the diastereomer rac-(S,RFc)-7 was reacted with

Scheme 7

Table 1. Methoxy/Phosphino and Amino/Phosphino Exchange Reactionsa

aReaction conditions. Solvent: acetic acid; 11, 20, 21: 80 �C, 18 h; 7: 60 �C, 18 h; 8, 22: 60 �C, 24 h. bR0 =Ph. cR0 =3,5-(CF3)2C6H3.dR0 =Cy. eR0 =

tBu. fData taken from ref 1. gRef 4a. h Isolated yield.


diphenylphosphine, two diastereomeric products were ob-tained with full conversion, although themajor diastereomerrac-(R,RFc)-2 was identical to the product obtained fromrac-(R,RFc)-7. Therefore, the major diastereomer must beformed with inversion of configuration. The trimethylsilyl-substituted ferrocene (S,SFc)-8, which is structurally relatedto rac-(S,RFc)-7, was also reacted with HPPh2 and with[3,5-(CF3)2C6H3]2PH in acetic acid. In both cases only onediastereomer was formed, and this was obtained in low yield,i.e., 3a (26%) and 3b (17%). The absolute configuration ofthe product was determined by converting 3b into its di-chloropalladium complex [PdCl2(3b)] by treatment with[PdCl2(MeCN)2]. An X-ray diffraction study gave the abso-lute configuration of ligand 3b as (R,SFc), and this resultsfrom inversion of configuration at the benzylic carbon.

Discussion

In summary, for all of the derivatives investigated thestereochemical course of the R-dimethylamino/phosphinoand R-methoxy/phosphino exchange reactions dependedprimarily on the relative configuration of the substrates,their substitution pattern, and, to a lesser extent, the nucleo-phile used. All derivatives that had the relative configurationof type A [Scheme 8, e.g., rac-(R,SFc)-20 or rac-(R,RFc)-7]reacted with secondary phosphines in acetic acid with cleanretention of configuration.In the reaction of substrates with a type B relative config-

uration [e.g., rac-(S,SFc)-20, rac-(S,RFc)-7, or (R,RFc)-11],the stereochemical course of the substitution reaction wasstrongly dependent on the substrate substitution patternof the ligand backbone. For example, all benzylferrocenyl-based and disubstituted derivatives [(R)-6 and rac-(S,SFc)-20-22)] reacted mainly with retention of configuration, but,with the exception of (R)-6, a small amount of a secondisomerwas also formedwith inversion of configuration at thebenzylic R-position. Only for the trisubstituted derivativesrac-(S,RFc)-7 and (S,SFc)-8 did the exchange reaction proceedto eithermainly rac-(R,RFc)-2, rac-(S,RFc)-7, [PdCl2((R,SFc)-3b)],with inversion of configuration. These latter results parallel

the observation of Fukuzawa12 that the trisubstitutedbenzylferrocenyl-based derivative (R,RFc)-18 is transformedinto (S,RFc)-19 with inversion of configuration (Scheme 3).Aminophosphines (R,RFc)-11 reacted in a similar way to

the R-methoxy-substituted derivatives rac-(S,SFc)-20-22 inthat reactionwith diphenylphosphine and dicyclohexylphos-phine gave a single product with clean retention of config-uration [(R,RFc)-36a and 36b]. Only when the very bulky di-tert-butylphosphine was used as the nucleophile was a smallamount of the diastereomer (S,RFc)-36c formed with inver-sion of configuration along with the major product diaste-reomer (R,RFc)-36c.According to a mechanistic proposal put forward by Ugi

and co-workers,5,17 these types of exchange reactions areexpected to proceed through a two-step process with thefirst step involving the participation of the ferrocene unit(Scheme 8). Depending on the relative configuration (typeAor typeB) and on the preferred conformation of the reactant,in the first step the leaving group dissociates from theR-carbon, and this leads to an intermediate carbocation ora corresponding ion pair (Scheme 8, I or II). These inter-mediates are thought to be stabilized by the participation ofthe ferrocene unit. Provided that isomerization of I and II

does not take place and provided that the nucleophileapproaches the cationic intermediate on a trajectory comingfrom above the Cp ring to the R-position, products withoverall retention of configuration are obtained. It hasalready been pointed out by Ugi that the interconversionof intermediates I and II may occur under conditions thatfavor a long lifetime for these intermediates. In addition, onemight anticipate that in cases where interconversion of I

and II is feasible, for steric reasons cation I should be morefavored than II since in cation II close contacts of ste-rically demanding substituents R1 and R0 may lead to strongrepulsive interactions.On the basis of this mechanistic proposal, the process

involving reactants of type A should be easiest, since in the

Scheme 8. Ugi’s Reaction Mechanisma

aAdopted from ref 5.

(17) Chen, C.; Fr€ohlich, R.; Kehr, G.; Erker, G. Organometallics2008, 27, 3248–3253.


first step themore stable intermediate I is formed. Indeed, allsubstrates of type A [rac-(R,RFc)-7, (S,RFc)-11, rac-(R,SFc)-20-22] resulted in products with full conversion (and highisolated yield) and with clean retention of configuration. Inthis context it is worth mentioning that, according to thereported molecular structures of (S,RFc)-11

18 and (R,SFc)-218a

in the solid state, these compounds adopt conformations inwhich the orientation of the side chain already predefinesthe structure of intermediate I with the NMe2 or OMegroup pointing straight above Cp and the side chain methylor phenyl group pointing away from the diphenylphos-phino unit (for a schematic representation see Scheme 8,first line).The exchange reaction with derivatives of type B, which

have either a side chain methyl group [(R,RFc)-11] or anunsubstituted side chain phenyl group [rac-(S,SFc)-20-22](Scheme 8,R2=H), resulted in all but two cases [(R,RFc)-11/HPPh2, (R,RFc)-11/HPCy2] in a mixture of two diastereo-mers with the major isomer always being formed withretention of configuration at the benzylic carbon. Thisstereochemical course is consistent with a reaction pathwayof reactant (type B) f intermediate II f product (type B).In the cases of the trisubstituted type B derivatives rac-

(S,RFc)-7 and (S,SFc)-8, which differ from substrates 20-22

by an additional substituent at the side chain phenyl ring,the product distribution changes. Reaction of rac-(S,RFc)-7again gives two product isomers with quantitative conver-sion, but in this case the main product is formed withinversion of configuration. The exchange reactions with(S,SFc)-8 proceed exclusively with inversion of configurationto give (R,SFc)-3a and (R,SFc)-3b as the final products.According to Ugi’s proposal, the formation of the mainproducts would involve the reaction sequence reactant(type B) f intermediate II f intermediate I f product(type A). In these cases an isomerization process leadingfrom intermediate II mainly to I must be involved. Such aprocess seems to be plausible, since for intermediate II onewould expect significant steric interactions between the orthosubstituent at ferrocene and the ortho substituent at the sidechain phenyl ring (Scheme 8, substituents R1 and R0).However, considering the molecular structure of rac-

(S,RFc)-7 in the solid state we questioned whether an alter-native pathwaymay lead directly from 7 to intermediate I. Asdepicted in Figure 2 and shown schematically in Scheme 9,derivative (S,RFc)-7 belongs to type B reactants but adopts aconformation in which the methoxy group points below Cpand toward the ethyl substituent, while the side chain phenylring is turned away from the ferrocenyl ethyl group. In thisconformation the intermediate I is already preformed andan acid-mediated dissociation of the leaving group woulddirectly lead to intermediate I.On the basis of the results of our stereochemical study we

conclude that the synthesis of catalyst ligands 2, 3, or relatedderivatives can be carried out starting from precursors 7, 8,or similar derivatives having either (R,RFc) or (R,SFc) rela-tive configuration. However, since one diastereomeric pre-cursor (of type A relative configuration) reacts with cleanretention and the second one mainly with inversion of con-figuration (type B diastereomer), in both cases the prod-uct of the same relative configuration is obtained. Thereforeonly one stereoisomer is obtainable stereoselectively through

this route. In this respect the trimethylsilyl-substituted di-phosphines (R,SFc)-3a and (R,SFc)-3b have been preparedin their enantiopure form. Further ligand synthesis andcatalytic testing is currently under investigation.

Summary

The exchange reaction of ferrocenyl R-methoxy orR-dimethylamino substituents by secondary phosphines inacetic acid has been studied on pairs of diastereomers that allhave either a ferrocenylethyl or benzylferrocenyl backbone.The stereochemical course of such reactions was found todepend strongly on the relative configuration of the startingmaterial and in the case of benzylferrocenyl-based deriv-atives also on their substitution pattern. With PPFA-typestarting materials the reaction always proceeded with reten-tion of configuration regardless of which PPFA diastereo-mer was used. Only when (R,RFc)-PPFA was reacted withthe sterically very demanding di-tert-butylphosphine inacetic acid was a small amount of the diastereomer formedwith inversion of configuration along with themain product.The results obtained with benzylferrocenyl-based deriv-

atives were found to fall into three categories. Diastereomerswith a type A relative configuration [represented by, e.g.,(R,SFc)-1-diphenylphosphino-2-[R-methoxyphenylmethyl]-ferrocene, (R,SFc)-21] always gave the productwith retentionof configuration regardless of the substitution pattern. In thecase of substrates with a type B relative configuration [e.g.,(S,SFc)-21] the exclusively at ferrocene substituted deriv-atives gave amixture of diastereomers with themain productformed with retention of configuration. With the trisubsti-tuted ferrocenes of type B, all of which bear substituents atferrocene and at the side chain phenyl ortho position, prod-ucts were formed mainly or exclusively with inversion ofconfiguration.

Experimental Part

General Considerations. NMR spectra were recorded onBruker DRX-400 andDRX-600 spectrometers in CDCl3. Chem-ical shifts (δ) are given relative to CHCl3 (

1H: 7.24 ppm), CDCl3(13C: 77.0 ppm), and 85% H3PO4 (

31P: 0 ppm). The couplingconstants in 13C{1H} spectra are due to 13C-31P coupling. Forsignal assignment the following termswere used: s, bs, d, dd, t, q,and m refer to singlet, broad singlet, doublet, doublet of dou-blets, triplet, quartet, and multiplet, respectively. The terms

Scheme 9

(18) Einstein, F. W. B.; Willis, A. C. Acta Crystallogr. 1980, B36,39–43.


PhA-D are used for phenyl or aryl groups of diphenylphosphinoor diarylphosphino units. In this respect, superscripts A-D areused to distinguish between rings attached to different phos-phorus atoms. A general atom-numbering scheme used for pro-ton and carbon assignment is given in Figure 3. Melting pointswere determined on a Kofler melting point apparatus and areuncorrected.Mass spectra were recorded onFinniganMAT 900or MAT 95 spectrometers. Optical rotations were measured ona Perkin-Elmer 241 polarimeter. HPLC was performed in anisocratic mode on Agilent systems with Daicel Chiralcel OD-Hcolumns and mixtures of n-heptane and propan-2-ol. All reac-tions required inert conditions and were carried out under anargon atmosphere using standard Schlenk techniques. All sol-vents were dried by standard procedures and distilled beforeuse.19 Chromatographic separations were performed undergravity on either aluminum oxide 90 (Merck) or silica (Merck,40-63 μm). Abbreviations: DEE, diethyl ether; PE, petroleumether; DCM, dichloromethane; EA, ethyl acetate. LiTMP wasprepared according to a literature procedure.13b

The following substances were prepared according to pub-lished procedures: rac-23,20 rac-26,14 (SFc)-30,

21 (R,RFc)-11.6

Compound 24 was purchased from Sigma.General Procedure A. A mixture of methyl ether (0.5 mmol)

and diphenylphosphine (0.6 mmol) in acetic acid (2 mL) wasdegassed three times and heated for an appropriate time. Aftercooling, the solvent was removed under reduced pressure andthe remaining semisolid was redissolved in DCM (2 mL). Analiquot was checked by NMR to determine the product dis-tribution, and the solvent was again removed under reducedpressure. The residue was treated with a 1.0 M solution ofborane in THF (5 mL) and stirred for a further 2 h. Waterwas added dropwise to quench the reaction, and DEE was usedfor extraction. The combined organic layers were washed withwater and brine and dried over MgSO4, and the solvents wereremoved on a rotary evaporator. The crude product was puri-fied as described.General Procedure B.A 60% dispersion of sodium hydride in

mineral oil (50mmol) was placed in a Schlenk flask, andmineraloil was removed by washing with PE (3 � 5 mL). The appro-priate alcohol (33mmol) dissolved inTHF (15mL)was added tothe flask containing the sodium hydride, and the mixture washeated under reflux for 2.5 h. After cooling to 0 �C iodomethane(50 mmol) was added dropwise and the resulting mixture wasstirred at rt for 3 h. The reaction was then quenched carefullyby the addition of methanol, THF was removed on a rotaryevaporator, and the residue was extracted with DEE (2 � 100mL). The combined organic layers were washed with water andbrine anddried overMgSO4, and the solventwas removed underreduced pressure. The crude product was purified as described.rac-(S,RFc)-1-Ethyl-2-[r-diphenylphosphino-(2-diphenylphos-

phinophenyl)methyl]ferrocene, rac-(S,RFc)-2. This compoundwas obtained as a byproduct (see preparation of rac-(R,RFc)-2

method B) and could not be separated from the main product.1H NMR (400 MHz, CDCl3): (selected signals) δ 0.47 (t, J =7.4 Hz, 3H, CH3), 0.89-1.00 (m, 1H, CHAHB), 1.24-1.36 (m,1H, CHAHB), 3.52 (s, 5H, Cp0), 3.89 (m, 1H, CpH), 4.77 (m, 1H,CpH), 6.25 (dd, J=8.7Hz, J=6.1Hz, 1H,H6). 31PNMR (162MHz, CDCl3): δ -18.6 (s), 5.8 (s).

rac-(R,RFc)-1-Ethyl-2-[r-diphenylphosphino-(2-diphenylphos-phinophenyl)methyl]ferrocene, rac-(R,RFc)-2. Method A:Amix-ture of rac-(R,RFc)-7 (290 mg, 0.5594mmol) and diphenylphos-phine (156 mg, 0.8391 mmol) in freshly distilled acetic acid(4 mL) was degassed three times and stirred overnight at 60 �Cunder argon. In order to determine the product distribution,the solvent was removed under reduced pressure and the yellowresidue was dissolved in DCM (2mL). An aliquot was analyzedby NMR, and this revealed complete conversion and fullretention of configuration (331 mg, 0.4922 mmol, 88% yield).Method B: A mixture of rac-(S,RFc)-7 (200 mg, 0.3858 mmol)and diphenylphosphine (108 mg, 0.5787 mmol) in freshly dis-tilled acetic acid (3 mL) was degassed three times and stirredovernight at 60 �C under argon. In order to determine theproduct distribution, the solvent was removed under reducedpressure and the yellow residue was dissolved in DCM (2 mL).An aliquot was analyzed by NMR, and this revealed completeconversion and showed the diastereomeric ratio of rac-(R,RFc)-2and rac-(S,RFc)-2 to be 2.6:1 (de = 72%). Mp: 185-188 �C(dec). 1H NMR (400 MHz, CDCl3): δ 0.79 (t, J = 7.4 Hz, 3H,CH3), 1.73-1.86 (m, 1H, CHAHB), 2.09-2.22 (m, 1H,CHAHB), 3.26 (s, 5H, Cp0), 3.71-3.77 (m, 1H, H5), 3.96-4.01(m, 1H,H4), 4.52-4.59 (m, 1H,H3), 5.87 (dd, J=10.9Hz, J=7.6Hz, 1H, H6), 6.58-6.68 (m, 2H, Ph), 7.00-7.09 (m, 2H, Ph),7.10-7.27 (m, 9H, H9 þ H10 þ Ph), 7.28-7.43 (m, 7H, Ph),7.47-7.56 (m, 1H, H11), 7.57-7.64 (m, 2H, Ph), 8.11-8.20 (m,1H,H12). 13C{1H}NMR (100.6MHz, CDCl3): δ 13.2 (s, CH3),20.1 (d, J= 4.4 Hz, CHAHB), 39.0 (dd, J= 29.3 Hz, J = 14.4Hz, C6), 64.2 (s, C5), 65.6 (s, C4), 67.6 (d, J=15.4Hz, C3), 68.6(s, Cp0), 90.3 (d, J = 2.1 Hz, C1), 90.9 (d, J = 20.5 Hz, C2),126.2 (s, C10), 127.5 (s, Ph-para), 127.7 (d, J = 7.3 Hz, Ph-meta), 127.8-128.0 (m, 2 � Ph-meta), 128.2 (s, Ph-para), 128.6(s, Ph-para), 128.7 (d, J = 5.2 Hz, Ph-meta), 129.2 (s, C11 þPh-para), 130.9 (dd, J = 15.8 Hz, J = 4.8 Hz, C12), 132.7 (d,J = 17.4 Hz, Ph-ortho), 134.1 (dd, J = 19.2 Hz, J = 3.6 Hz,Ph-ortho), 134.4 (d, J = 19.4 Hz, Ph-ortho), 134.6 (dd, J =10.0 Hz, J=3.2 Hz, Ph-ipso), 134.9 (d, J=21.5 Hz, Ph-ortho),135.2 (s, C9), 136.1 (d, J=12.0 Hz, Ph-ipso), 136.4 (d, J=15.7Hz, Ph-ipso), 136.9 (d, J=18.9 Hz, C8), 139.1 (d, J=10.5 Hz,Ph-ipso), 151.4 (dd, J = 27.3 Hz, J = 12.5 Hz, C7). 31P NMR(162 MHz, CDCl3): δ -19.1 (s, C8-P), 17.2 (s, C6-P). HR-MS(EI, 40 �C): m/z= [M]þ calcd 672.1799 for C43H38FeP2, found672.1791.

(R,SFc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)-(2-diphenylphosphinophenyl)methyl]ferroceneTrihydridoboron, (R,SFc)-3a(BH3).Diphenylphosphine (1.59 g, 8.534mmol) was added toa solution of (S,SFc)-8 (3.20 g, 5.689 mmol) in freshly distilledacetic acid (60 mL). The resulting mixture was degassed threetimes and kept at 60 �C for 24 h. After cooling, the solvent wasremoved under reduced pressure and the residuewas redissolvedin a 1.0 M solution of borane in THF (56 mL, 56 mmol). Afterstirring for 2 h at rt the reaction was quenched by dropwiseaddition of water. The solvent was removed on a rotary evap-orator, and the residue was extracted with EA (2 � 200 mL).The combined organic layers were washed with water and brineand dried over MgSO4, and the solvents were removed underreduced pressure. The crude product was subjected to chroma-tography on aluminum oxide 90 using PE/EA= 30:1f 20:1 aseluent to give the title compound as a yellow solid (1.09 g, 1.492mmol, 26% yield). Mp: 183 �C. 1H NMR (400MHz, CDCl3): δ-0.01 (s, 9H, Si(CH3)3), 0.61-1.64 (bs, 3H, P-BH3), 3.40 (s, 5H,Cp0), 4.01 (dd, J = 2.5 Hz, J = 1.0 Hz, 1H, H2), 4.48 (t, J =2.5 Hz, 1H, H3), 4.93-4.95 (m, 1H, H4), 6.04 (dd, J=15.1 Hz,J = 10.2 Hz, 1H, H6), 6.64 (dd, J = 8.3 Hz, J = 7.0 Hz, 2H,

Figure 3. Atom-numbering scheme for NMR structure assign-ments for 2, 3, 7, 8, 20-22, 25, 27-29, 31-35 (left) and 36

(right).

(19) Perrin, D. D.; Armarego, W. L. F. Purification of LaboratoryChemicals; Pergamon Press: Oxford, 1993.(20) Mashburn, T. A.; Hauser, C. R. J. Org. Chem. 1961, 26, 1671–

1672.(21) Riant, O.; Samuel, O.; Flessner, T.; Taudien, S.; Kagan, H. B.

J. Org. Chem. 1997, 62, 6733–6745.


PhA-ortho), 7.12 (dd, J = 8.3 Hz, J = 7.0 Hz, 2H, PhA-meta),7.15-7.23 (m, 7H, PhC-ortho þ PhD-meta þ PhC-meta þPhA-para), 7.24-7.28 (m, 3H, H9 þ H10 þ PhD-para),7.28-7.31 (m, 1H, PhC-para), 7.32-7.36 (m, 3H, PhB-meta þPhB-para), 7.43-7.56 (m, 3H, H11 þ PhB-ortho), 7.82 (dd, J=11.3 Hz, J = 9.6 Hz, 2H, PhD-ortho), 8.09-8.16 (m, 1H, H12).13C{1H} NMR (100.6 MHz, CDCl3): δ 1.7 (d, J = 4.6 Hz,Si(CH3)3), 41.3 (dd, J=23.9Hz, J=25.3Hz, C6), 68.7 (s, Cp0),71.3 (s, C3), 72.7 (d, J = 2.5 Hz, C4), 73.7 (s, C2), 74.7 (d, J =1.6 Hz, C1), 92.1 (d, J = 2.8 Hz, C5), 126.2 (d, J = 51.6,PhC/D-ipso), 127.3 (d, J = 2.3 Hz, PhA-para), 127.5 (s, C10),127.8, 127.9, 128.3 (3d, J=15.5 Hz, J=11.3 Hz, J=10.0 Hz,PhA-meta þ PhC-meta þ PhD-meta), 128.6 (d, J = 7.5 Hz,PhB-meta), 128.7 (s, C11), 129.0 (s, PhB/C-para), 128.9 (d, J =51.3 Hz, PhC/D-ipso), 130.5 (d, J = 2.4 Hz, PhB/C-para), 131.3(d, J = 2.3 Hz, PhD-para), 132.5 (d, J = 16.6 Hz, PhA-ortho),132.6 (s, C12), 134.1 (d, J = 8.5 Hz, PhC-ortho), 134.3 (d, J =20.0 Hz, PhB-ortho), 134.8 (dd, J = 8.5 Hz, J = 3.9 Hz,PhD-ortho þ C8), 136.5 (d, J = 12.3 Hz, PhB-ipso), 136.8 (s,C9), 139.0 (d, J=9.9Hz, PhA-ipso), 147.0 (dd, J=29.9Hz, J=3.1 Hz, C7). 31P NMR (162 MHz, CDCl3): δ -19.2 (s, C8-P),30.6 (bs, C6-P). PhA þ PhB connected to C8-P, PhC þ PhD

connected to C6-P. HR-MS (ESI-MS, MeOH/MeCN): m/z =[M]þ calcd 730.2217 for C44H45BFeP2Si, found 730.2224. [R]20λ(nm): -53.3 (589), -57.6 (578), -82.1 (546) (c 0.988, CH2Cl2).(R,SFc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)-(2-

diphenylphosphinophenyl)methyl]ferrocene, (R,SFc)-3a. A solu-tion of (R,SFc)-(3a(BH3)) (856 mg, 1.172 mmol) in diethylamine(100 mL) was stirred at rt overnight. The solvent was removedusing a rotary evaporator, and the residue was chromato-graphed under inert conditions on aluminum oxide 90 usingPE/EA = 40:1 as eluent to give the title compound as a yellowsolid (626 mg, 0.8735 mmol, 75% yield). Mp: 75 �C. 1H NMR(400 MHz, CDCl3): δ 0.14 (s, 9H, Si(CH3)3), 3.57 (s, 5H, Cp0),4.05-4.08 (m, 1H, H2), 4.39 (t, J=1.2 Hz, 1H, H3), 4.46-4.49(m, 1H, H4), 5.82 (dd, J = 9.8 Hz, J = 2.4 Hz, 1H, H6),6.76-6.84 (m, 4H, PhD-ortho þ PhB-ortho), 7.00-7.07 (m,4H, PhD-meta þ PhC-meta), 7.12-7.18 (m, 4H, PhB-meta þPhD-para þ PhC-para), 7.19-7.23 (m, 2H, H10 þ PhB-para),7.24-7.29 (m, 3H, H9 þ PhC-ortho), 7.30-7.35 (m, 3H,PhA-meta þ PhA-para), 7.37-7.46 (m, 3H, H11 þ PhA-ortho),7.83-7.90 (m, 1H,H12). 13C{1H}NMR (100.6MHz, CDCl3): δ1.6 (s, Si(CH3)3), 42.4 (dd, J= 23.0 Hz, J= 25.5 Hz, C6), 68.5(s, Cp0), 70.4 (s, C3), 71.1 (d, J= 7.3 Hz, C4), 73.5 (s, C1), 73.5(s, C2), 96.2 (d, J = 14.5 Hz, C5), 126.2 (s, C10), 127.5 (d, J =6.5 Hz, PhC/D-meta), 127.7 (s, PhB-para), 127.9, 128.0 (2d, J =8.1 Hz, J = 7.0 Hz, PhC/D-meta þ PhB-meta), 128.4, 128.4,128.5, 128.5 (4s, C11þPhD-paraþPhC-paraþPhA-para), 128.8(d, J= 6.4 Hz, PhA-meta), 130.8 (dd, J= 13.7 Hz, J= 5.5 Hz,C12), 133.1 (d, J= 18.7 Hz, PhB-ortho), 133.9 (d, J= 19.6 Hz,PhA-ortho), 134.6 (d, J=19.8Hz, PhD-ortho), 134.9 (d, J=19.3Hz, C8), 135.0 (dd, J= 21.0 Hz, J= 2.5 Hz, PhC-ortho), 136.0(d, J = 21.9 Hz, Ph-ipso), 136.3 (s, C9), 137.4 (d, J = 13.1 Hz,Ph-ipso), 137.5 (d, J=13.1 Hz, Ph-ipso), 139.0 (d, J=11.0 Hz,Ph-ipso), 150.4 (dd, J = 28.0 Hz, J = 9.9 Hz, C7). 31P NMR(162MHz, CDCl3): δ-19.7 (d, J=5.1 Hz, C8-P), 21.1 (d, J=5.1 Hz, C6-P). PhA þ PhB connected to C8-P, PhC þ PhD

connected to C6-P. HR-MS (ESI-MS, MeOH/MeCN): m/z =[M þ H þ 2O]þ calcd 749.1858 for C44H43FeO2P2Si, found749.1863. [R]20λ (nm): -25.4 (589), -26.4 (578), -29.5 (546)(c 1.071, CH2Cl2).(R,SFc)-1-Trimethylsilyl-2-[r-bis(3,5-bistrifluoromethylphenyl)-

phosphino-(2-diphenylphosphinophenyl)methyl]ferrocene, (R,SFc)-3b. To a solution of (S,SFc)-8 (3.20 g, 5.689 mmol) in freshlydistilled acetic acid (60 mL) was added bis[3,5-bis(trifluoro-methyl)phenyl]phosphine (3.91 g, 8.535 mmol), and the result-ing mixture was degassed three times. After heating at 60 �C for24 h the reaction was cooled to rt and the solvent was removedunder reduced pressure. The residue was extracted with DEE(2 � 100 mL), and the combined organic layers were washed

with saturated sodium bicarbonate, water, and brine and driedover MgSO4. The solvents were removed on a rotary evapora-tor, and the crude product was purified by chromatography onaluminum oxide 90 using PE/EA = 80:1 as eluent to give thepure product as a yellow solid (969 mg, 0.9801 mmol, 17%yield). Mp: 65 �C. 1H NMR (400 MHz, CDCl3): δ 0.28 (s, 9H,Si(CH3)3), 3.87 (s, 5H, Cp0), 4.11-4.14 (m, 1H, H4), 4.25-4.28(m, 1H,H2), 4.48 (t, J=2.4Hz, 1H,H3), 6.14 (dd, J=11.7Hz,J = 4.8 Hz, 1H, H6), 6.93 (m, 2H, PhB-ortho), 7.07 (d, J =6.2 Hz, 2H, PhD-ortho), 7.12 (m, 2H, PhB-meta), 7.18-7.24 (m,3H, PhA-ortho þ PhB-para), 7.26-7.30 (m, 3H, PhA-meta þPhA-para), 7.31-7.44 (m, 6H, C9, C10, C11, C12þ PhC-ortho),7.69 (s, 1H, PhD-para), 7.72 (s, 1H, PhC-para). 13C{1H} NMR(100.6 MHz, CDCl3): δ 1.2 (s, Si(CH3)3), 43.5 (dd, J=27.1 Hz,J=29.0 Hz, C6), 69.0 (s, Cp0), 71.0 (d, J=1.7 Hz, C4), 71.4 (s,C3), 72.9 (d, J=2.4 Hz, C1), 75.0 (s, C2), 93.2 (d, J=10.3 Hz,C5), 122.9 (q, J=273.3Hz, CF3), 123.0 (q, J=273.6Hz, CF3),123.1-123.5 (m, PhC-para þ PhD-para), 127.5 (s, C10/C11),128.3, 128.7, 128.8 (3s, C10/C11þ PhA-paraþ PhB-para), 128.3(d, J = 7.2 Hz, PhB-meta), 128.5 (d, J = 6.0 Hz, PhA-meta),130.2 (dd, J=7.0Hz, J=5.0Hz, C12), 131.0 (dd, J=26.0Hz,J=7.9Hz,C-CF3), 131.1 (dd, J=26.8Hz, J=6.9Hz,C-CF3),133.1 (d, J = 17.9 Hz, PhA-ortho), 133.5 (d, J = 20.3 Hz,PhB-ortho), 134.4-134.9 (m, PhC-ortho þ PhD-ortho), 135.6 (d,J=13.5 Hz, C8), 136.3 (d, J=10.0 Hz, Ph-ipso), 136.6 (s, C9),136.9 (d, J=16.9 Hz, Ph-ipso), 137.1 (d, J=17.9 Hz, Ph-ipso),137.5 (d, J= 11.0 Hz, Ph-ipso), 146.5 (d, J= 31.2 Hz, C7). 31PNMR (162MHz, CDCl3): δ-20.1 (d, J=12.9 Hz, C8-P), 13.7(d, J = 12.9 Hz, C6-P). PhA þ PhB connected to C8-P, PhC þPhD connected to C6-P. HR-MS (ESI-MS, MeOH/MeCN):m/z = [M]þ calcd 988.1377 for C48H38F12FeP2Si, found988.1359. [R]20λ (nm): þ109.1 (589), þ119.4 (578), þ175.3(546) (c 0.955, CH2Cl2).

rac-(S,RFc)-1-Ethyl-2-[r-methoxy(diphenylphosphinophenyl)-methyl]ferrocene, rac-(S,RFc)-7. A 1.6 M solution of n-BuLi inhexane (2.11 mL, 3.383 mmol) was added dropwise to a stirredsolution of rac-(S,RFc)-29 (1.331 g, 3.222mmol) in THF (15mL)at -78 �C, and the mixture was stirred for 30 min. Chlorodi-phenylphosphine (924 mg, 4.189 mmol) was added dropwise at-78 �C, and stirring was continued for a further 30 min. Afterwarming to rt the mixture was stirred for a further 1 h followedby quenching by the dropwise addition of water. The productwas extracted with EA (2 � 50 mL), and the combined organiclayers were washed with water and brine and dried overMgSO4.The solvents were removed under reduced pressure, and theresiduewas subjected to chromatography on aluminumoxide 90using PE/EA = 30:1 as eluent to give the product as a yellowfoam (0.903 g, 1.742 mmol, 54% yield). Mp: 134 �C. 1H NMR(400 MHz, CDCl3): δ 0.88 (t, J= 7.5 Hz, 3H, CH3), 1.98-2.11(m, 1H, CHAHB), 2.27-2.40 (m, 1H, CHAHB), 3.22 (s, 3H,OCH3), 3.90-3.95 (m, 1H, H4), 3.97-4.02 (m, 1H, H5),4.05-4.09 (m, 1H, H3), 4.15 (s, 5H, Cp0), 6.11 (d, J = 8.0 Hz,1H, H6), 6.98-7.04 (m, 1H, H9), 7.13-7.19 (m, 1H, H10),7.31-7.36 (m, 11H, H11 þ 2 � Ph-ortho þ 2 � Ph-meta þ 2 �Ph-para), 7.37-7.42 (m, 1H, H12). 13C{1H} NMR (100.6MHz,CDCl3): δ 13.9 (s, CH3), 21.1 (d, J = 3.8 Hz, CHAHB), 57.2 (s,OCH3), 64.8 (s, C4), 67.1 (s, C5), 67.4 (s, C3), 69.2 (s, Cp

0), 77.7(d, J = 26.4 Hz, C6), 88.1 (s, C1), 89.3 (s, C2), 127.5 (s, C10),127.9 (d, J=5.4 Hz, C12), 128.3-128.6 (m, 2� Ph-metaþ 2�Ph-para), 129.4 (s, C11), 133.7 (d, J = 8.9 Hz, Ph-ortho), 133.8(s, C9), 133.9 (d, J = 9.1 Hz, Ph-ortho), 135.5 (d, J = 14.3 Hz,C8), 136.8 (d, J = 10.7 Hz, Ph-ipso), 137.1 (d, J = 10.4 Hz,Ph-ipso), 147.1 (d, J = 24.0 Hz, C7). 31P NMR (162 MHz,CDCl3): δ -17.1 (s). HR-MS (EI, 30 �C): m/z = [M]þ calcd518.1462 for C32H31FeOP, found 518.1452.

rac-(R,RFc)-1-Ethyl-2-[r-methoxy(diphenylphosphinophenyl)-methyl]ferrocene, rac-(R,RFc)-7. A 1.6 M solution of n-BuLi inhexane (1.97 mL, 3.146 mmol) was added to a solution of rac-(R,RFc)-29 (1.238 g, 2.997mmol) inTHF (15mL) at-78 �C, andthe mixture was stirred for 30 min. Chlorodiphenylphosphine


(860 mg, 3.896 mmol) was added dropwise at -78 �C, andstirring was continued for a further 30 min. After warming tort the mixture was stirred for 1 h followed by quenching bydropwise addition of water. The product was extracted with EA(2� 50mL), and the combined organics werewashedwithwaterand brine and dried over MgSO4. The solvents were removedunder reduced pressure, and the residue was subjected to chro-matography on aluminum oxide 90 using PE/EA = 30:1 aseluent to give the product as an orange-yellow, viscous oil(0.890 g, 1.717 mmol, 57% yield). 1HNMR (400MHz, CDCl3):δ 1.22 (t, J = 7.5 Hz, 3H, CH3), 2.53-2.68 (m, 2H, CHAHB),2.71 (s, 3H, OCH3), 3.92 (s, 5H, Cp0), 4.01-4.03 (m, 1H, H4),4.06-4.09 (m, 1H,H3), 4.11-4.14 (m,1H,H5), 5.93 (d,J=6.6Hz,1H, H6), 7.03-7.07 (m, 1H, H9), 7.31-7.26 (m, 1H, H10),7.32-7.43 (m, 10H, 2�Ph-orthoþ 2�Ph-metaþ 2�Ph-para),7.42-7.46 (m, 1H, H11), 7.66-7.72 (m, 1H, H12). 13C{1H}NMR (100.6MHz, CDCl3): δ 14.6 (s, CH3), 21.1 (d, J=3.7Hz,CHAHB), 56.3 (s, OCH3), 66.2 (s, C4), 66.8 (d, J= 1.5 Hz, C3),67.5 (s, C5), 69.3 (s, Cp0), 77.9 (d, J=24.4 Hz, C6), 87.4 (s, C2),90.0 (s, C1), 127.7 (s, C10), 127.9 (d, J = 5.1 Hz, C12),128.4-128.7 (m, C11 þ 2 � Ph-para þ Ph-meta), 129.0 (d,J = 14.5 Hz, Ph-meta), 133.4 (s, C9), 134.0 (d, J = 19.3 Hz,Ph-ortho), 134.4 (d, J=20.4Hz, Ph-ortho), 135.8 (d, J=15.1Hz,C8), 136.5 (d, J = 12.1 Hz, Ph-ipso), 137.0 (d, J = 10.4 Hz,Ph-ipso), 146.6 (d, J = 22.3 Hz, C7). 31P NMR (162 MHz,CDCl3): δ -14.4 (s). HR-MS (EI, 30 �C): m/z = [M]þ calcd518.1462 for C32H31FeOP, found 518.1447.(S,SFc)-1-Trimethylsilyl-2-[r-methoxy(diphenylphosphinophenyl)-

methyl]ferrocene, (S,SFc)-8. A solution of (S,SFc)-32 (8.55 g,18.70 mmol) in THF (100 mL) was cooled to -78 �C, and a1.6M solution of n-BuLi in hexane (12.85 mL, 20.56 mmol) wasadded dropwise. Stirring was continued for 30 min followed bythe dropwise addition of chlorodiphenylphosphine (5.36 g,24.30 mmol). The mixture was stirred for a further 30 min at-78 �C and for 1 h at rt. The reaction was then quenched by theaddition of water, and THF was removed on a rotary evapora-tor. The residue was extracted with DEE (3� 150 mL), and thecombined organic layers were washed with water and brine.After drying over MgSO4 and removal of the solvent underreduced pressure the crude product was subjected to chroma-tography on aluminum oxide 90 using PE/DEE = 60:1 f 20:1as eluent to give the pure product as a yellow solid (9.00 g, 16.00mmol, 86% yield). Mp: 119 �C. 1HNMR (400MHz, CDCl3): δ0.13 (s, 9H, Si(CH3)3), 3.27 (s, 3H, OCH3), 4.09-4.12 (m, 1H,H4), 4.12-4.14 (m, 1H,H2), 4.20 (s, 5H,Cp0), 4.24 (t, J=2.3Hz,1H, H3), 5.94 (d, J = 7.6 Hz, 1H, H6), 6.96-7.02 (m, 1H),7.14-7.37 (m, 13H). 13C{1H} NMR (100.6MHz, CDCl3): δ 0.3(s, Si(CH3)3), 57.2 (s, OCH3), 68.7 (s, C3), 69.0 (s, Cp0), 69.1 (s,C1), 71.7 (d, J=2.2 Hz, C4), 74.6 (s, C2), 78.6 (d, J=23.8 Hz,C6), 95.1 (s, C5), 127.7 (s, 1C), 127.9 (d, J = 5.5 Hz, 1C),128.2-128.5 (m, 2� Ph-metaþ 2C), 128.9 (s, 1C), 133.7 (d, J=8.2 Hz, Ph-ortho), 133.9 (d, J=8.3 Hz, Ph-ortho), 134.0 (s, 1C),136.1 (d, J=14.2 Hz, Cq), 136.8 (d, J=10.0 Hz, Cq), 137.2 (d,J = 10.4 Hz, Cq), 147.2 (d, J = 24.2 Hz, Cq).

31P NMR (162MHz, CDCl3): δ -16.0 (s). HR-MS (ESI in MeOH/MeCN):m/z= [M]þ calcd 560.1591 for C33H35FeOPSi, found 560.1594.[R]20λ (nm): þ129.7 (589), þ139.5 (578), þ189.4 (546) (c 0.911,CH2Cl2).rac-(R,SFc)-1-Bromo-2-(r-methoxyphenylmethyl)ferrocene,

rac-(R,SFc)-20. This compound was obtained as a yellow solidfollowing a published procedure. Mp: 64-68 �C. Other analyt-ical data were in accordance with those reported in ref 11a.rac-(S,SFc)-1-Bromo-2-(r-methoxy-phenylmethyl)ferrocene,

rac-(S,SFc)-20. The product was obtained starting from rac-(S,SFc)-25 (3.518 g, 9.481 mmol) following general procedure B.Purification involved chromatography on silica using PE/DEE= 10:1 as eluent to give the title compound as an orange-red solid (3.247 g, 8.432 mmol, 89% yield). Mp: 99-101 �C.1HNMR (400MHz, CDCl3): δ 3.41 (s, 3H, OCH3), 4.07 (t, J=2.6 Hz, 1H, H3), 4.28 (s, 5H, Cp0), 4.25-4.30 (m, 1H, H4),

4.33-4.36 (m, 1H, H2), 5.06 (s, 1H, CHOCH3), 7.20-7.26 (m,1H, Ph-para), 7.27-7.32 (m, 2H, Ph-meta), 7.34-7.39 (m, 2H,Ph-ortho). 13C{1H} NMR (100.6 MHz, CDCl3): δ 56.9 (s,OCH3), 64.4 (s, C4), 65.8 (s, C3), 69.7 (s, C2), 71.4 (s, Cp0),77.9 (s, C1), 80.7 (s,CHOCH3), 90.2 (s, C5), 127.2 (s, Ph-ortho),127.7 (s, Ph-para), 128.3 (s, Ph-meta), 141.4 (s, Ph-ipso).HR-MS(ESI in MeOH/MeCN): m/z = [M]þ calcd 383.9814 forC18H17BrFeO, found 383.9821.

rac-(R,SFc)-1-Diphenylphosphino-2-(r-methoxyphenylmethyl)-ferrocene, rac-(R,SFc)-21. This compound was obtained as ayellow solid following a published procedure. Mp: 42-44 �C.Other analytical data were in accordance with those reported inref 11a.

rac-(S,SFc)-1-Diphenylphosphino-2-(r-methoxyphenylmethyl)-ferrocene, rac-(S,SFc)-21. A 1.6 M solution of n-BuLi in hexane(3.22 mL, 5.148 mmol) was added dropwise to a stirred solutionof rac-(S,SFc)-20 (1.802 g, 4.680 mmol) in THF (20 mL) at-78 �C. The resultingmixture was stirred at-78 �C for a further30 min followed by the dropwise addition of chlorodiphenyl-phosphine (1.34 g, 6.080mmol). Themixture was kept at-78 �Cfor 15 min and at rt for 1 h. Water was added to quench thereaction, and DEE caused phase separation. The aqueous phasewas extracted with DEE (2 � 100 mL), the combined organiclayers were washed with water and brine and dried overMgSO4,and the solvents were evaporated. The crude product was crys-tallized from heptane/toluene followed by short column chro-matography (aluminum oxide 90, PE/DEE= 16:1 as eluent) toremove traces of phosphine oxide. The product was obtained asan orange solid (1.793 g, 3.657 mmol, 78% yield). Mp: 176-179 �C. 1H NMR (400 MHz, CDCl3): δ 3.30 (s, 3H, OCH3),3.64-3.66 (m, 1H,H2), 4.12 (s, 5H, Cp0), 4.27 (t, J=2.5Hz, 1H,H3), 4.63-4.65 (m, 1H,H4), 5.22 (d, J=2.5Hz, 1H,CHOCH3),6.67-6.72 (m, 2H, PhB-ortho), 6.90-6.97 (m, 5H, PhC-ortho/meta þ PhC-para þ PhB-meta), 7.02-7.06 (m, 1H, PhB-para),7.07-7.11 (m, 2H, PhC-ortho/meta), 7.34-7.39 (m, 3H, PhA-meta þ PhA-para), 7.50-7.54 (m, 2H, PhA-ortho). 13C{1H}NMR (100.6 MHz, CDCl3): δ 56.5 (s, OCH3), 68.3 (d, J = 4.3Hz, C4), 69.1 (s, C3), 69.9 (s, Cp0), 71.0 (d, J=5.5 Hz, C2), 73.5(d, J=8.8Hz, C5), 80.9 (d, J=8.8Hz, CHOCH3), 97.6 (d, J=24.1 Hz, C1), 127.13 (s, PhB/C-para), 127.14 (s, PhB/C-para),127.49 (d, J = 5.7 Hz, PhB-meta), 127.51 (s, PhC-ortho/meta),127.7 (s, PhC-ortho/meta), 128.0 (d, J=7.9Hz, PhA-meta), 129.0(s, PhA-para), 131.9 (d, J = 18.7 Hz, PhB-ortho), 135.2 (d, J =20.9 Hz, PhA-ortho), 137.4 (d, J = 7.7 Hz, PhA-ipso), 138.7 (d,J=7.8 Hz, PhB-ipso), 141.2 (s, PhC-ipso). 31P NMR (162MHz,CDCl3): δ-21.5 (s). PhA and PhB connected to P. HR-MS (ESIinMeOH/MeCN):m/z=[M]þ calcd 490.1149 forC30H27FeOP,found 490.1140.

rac-(R,SFc)-1-Trimethylsilyl-2-(r-methoxyphenylmethyl)-ferrocene, rac-(R,SFc)-22. This compound was obtained as ayellow solid following a published procedure. Mp: 102-104 �C.Other analytical data were in accordance with those reported inref 11a.

rac-(S,SFc)-1-Trimethylsilyl-2-(r-methoxyphenylmethyl)ferro-cene, rac-(S,SFc)-22.A 1.6M solution of n-BuLi in hexane (3.65mL, 5.839 mmol) was added dropwise to a stirred solution ofrac-(S,SFc)-20 (2.044 g, 5.308 mmol) in THF (20mL) at-78 �C.The resulting mixture was stirred at-78 �C for a further 30 minfollowed by the dropwise addition of chlorotrimethylsilane(750 mg, 6.900 mmol). The mixture was kept at -78 �C for15min and at rt for 1 h.Water was added to quench the reaction,and DEE caused phase separation. The aqueous phase wasextracted with DEE (2 � 100 mL), the combined organic layerswere washed with water and brine and dried over MgSO4, andthe solvents were evaporated. The crude product was purified bychromatography on aluminum oxide 90 using PE/DEE= 10/:1as eluent to give the title compound as a red solid (2.092 g, 5.529mmol, 95%yield).Mp: 62-64 �C. 1HNMR(400MHz,CDCl3):δ 0.14 (s, 9H, Si(CH3)3), 3.39 (s, 3H, OCH3), 4.03-4.06 (m, 1H,H2), 4.20 (s, 5H, Cp0), 4.30 (t, J = 2.4 Hz, 1H, H3), 4.44-4.46


(m, 1H, H4), 4.98 (s, 1H, CHOCH3), 7.22-7.33 (m, 5H, Ph).13C{1H}NMR (100.6MHz, CDCl3): δ 0.3 (s, Si(CH3)3), 56.7 (s,OCH3), 68.9 (s, C1), 69.0 (s, Cp

0), 69.3 (s, C3), 70.0 (s, C4), 74.2(s, C2), 82.1 (s,CHOCH3), 96.4 (s, C5), 127.6 (s, Ph-para), 128.0(s, Ph-ortho/meta), 128.1 (s, Ph-ortho/meta), 141.9 (s, Ph-ipso).HR-MS (ESI inMeOH/MeCN):m/z=[M]þ calcd 378.1103 forC21H26FeOSi, found 378.1106.rac-(S,SFc)-1-Bromo-2-(r-hydroxyphenylmethyl)ferrocene,

rac-(S,SFc)-25.A solution of LiTMP in THF (0.73 M, 62.1 mL,45.30 mmol) was added to a stirred solution of 24 (6.00 g, 22.65mmol) in THF (20mL) at-78 �C, and the resultingmixture wasstirred at -78 �C for 30 min. After warming to -30 �C andstirring for a further 4 h, the red solution was again cooled to-78 �C and benzaldehyde (7.21 g, 67.95 mmol) was addeddropwise. After stirring at -78 �C for 15 min and at rt for 1 hthe mixture was quenched by the addition of water. DEE wasused for extraction, the combined organic layers were washedwith water and brine and dried over MgSO4, and the solventswere removed on a rotary evaporator. The diastereomersformed (de= 72%)were separated by column chromatographyon aluminum oxide 90 with DCM/PE = 5:1 f 1:0 as eluent togive rac-(S,SFc)-25 (5.844 g, 15.75mmol, 70%yield) followed byrac-(R,SFc)-25 (1.60 g, 4.30 mmol, 19% yield). Mp: 72-74 �C.1H NMR (400 MHz, CDCl3): δ 2.42 (d, J = 2.2 Hz, 1H, OH),4.13 (t, J=2.6Hz, 1H,H3), 4.26-4.29 (m, 1H,H4), 4.33 (s, 5H,Cp0), 4.47-4.50 (m, 1H, H2), 5.68 (d, J= 2.2 Hz, 1H, CHOH),7.21-7.27 (m, 1H, Ph-para), 7.27-7.33 (m, 2H, Ph-meta),7.38-7.43 (m, 2H, Ph-ortho). 13C{1H} NMR (100.6 MHz,CDCl3): δ 63.9 (s, C4), 66.2 (s, C3), 70.3 (s, C2), 70.6 (s, CHOH),71.1 (s, Cp0), 78.4 (s, C1), 92.4 (s, C5), 126.3 (s, Ph-ortho), 127.6(s, Ph-para), 128.3 (s, Ph-meta), 142.6 (s, Ph-ipso). HR-MS(ESI in MeOH/MeCN): m/z = [M]þ calcd 369.9656 forC17H15BrFeO, found 369.9645.rac-(S,RFc)-1-Ethyl-2-(r-hydroxy-2-bromophenylmethyl)ferro-

cene, rac-(S,RFc)-27.MethodA:Lithium chloride (200mg, 4.718mmol) was heated to 200 �C for 10min in vacuo, cooled to rt, anddissolved in a 2.0M solution of isopropylmagnesium chloride inTHF (2.30 mL, 4.600 mmol). The resulting mixture was stirredfor 15min and then cooled to-15 �C.Neat 1,2-dibromobenzene(1.07 g, 4.544 mmol) was then introduced dropwise by syringe,and the solution was stirred for 2 h at -15 �C. Aldehyde rac-28(1.00 g, 4.131 mmol) was dissolved in THF (5 mL) and addeddropwise by cannula to theGrignard reagent at-15 �C. Stirringwas continued for 15 min followed by warming to rt and furtherstirring for 30 min. The reaction mixture was then quenched bythe addition of saturated aqueous ammonium chloride solution.The product was extracted with DEE (2 � 100 mL), and thecombined organic layers were washed with water and brine anddried over MgSO4. The solvents were removed on a rotaryevaporator, and the resulting solid was subjected to columnchromatography on silica gel using PE/EA = 17:3 as eluent togive rac-(S,RFc)-27 as an orange-red oil (1.198 g, 3.002 mmol,73% yield).Method B:A solution of rac-26 (3.44 g, 11.74 mmol)in THF (12 mL) was degassed and cooled to-78 �C. Dropwiseaddition of a 1.6M solution of n-BuLi in hexane (7.34mL, 11.74mmol) led to the precipitation of a yellow-orange solid, andstirring was continued for 10 min. In a separate flask, 2-bromo-benzaldehyde (2.39 g, 12.92 mmol) was dissolved in THF(5 mL), and the solution was added dropwise at -78 �C to thelithium intermediate. Stirringwas continued for 30min followedby warming to rt and further stirring for 1 h. The reactionmixture was then quenched by the dropwise addition of water.The product was extracted with EA (2� 100 mL), and the com-bined organic layerswerewashedwithwater and brine and driedover MgSO4. The solvents were removed on a rotary evapora-tor, and the residue was chromatographed on aluminum oxide90 using PE/EA = 17:3 as eluent. rac-(S,RFc)-27: Rf = 0.40(1.78 g, 4.460mmol, 38%yield). rac-(R,RFc)-27:Rf=0.51 (1.93g, 4.836 mmol, 41% yield). 1HNMR (400MHz, CDCl3): δ 1.03(t, J = 7.5 Hz, 3H, CH3), 2.25-2.49 (m, 2H, CHAHB), 2.66

(d, J = 3.9 Hz, 1H, OH), 4.06-4.10 (m, 2H, H3 þ H4),4.18-4.21 (m, 1H, H5), 4.24 (s, 5H, Cp0), 5.84 (d, J = 3.9 Hz,1H,H6), 7.08-7.14 (m, 1H,H10), 7.24-7.30 (m, 1H,H11), 7.46(dd, J=7.8Hz, J=1.7Hz, 1H,H12), 7.51 (dd, J=8.0Hz, J=1.1 Hz, 1H, H9). 13C{1H} NMR (100.6MHz, CDCl3): δ 14.4 (s,CH3), 20.8 (s, CHAHB), 65.7 (s, C4), 66.6 (s, C3), 68.1 (s, C5),68.9 (s, Cp0), 69.2 (s, C6), 89.8 (s, C1), 92.3 (s, C2), 123.1 (s, C8),127.5 (s, C11), 128.7 (s, C12), 129.0 (s, C10), 132.6 (s, C9), 142.1(s, C7). HR-MS (EI 40 �C): m/z = [M]þ calcd 397.9969 forC19H19BrFeO, found 397.9966.

rac-(R,RFc)-1-Ethyl-2-(r-hydroxy-2-bromophenylmethyl)ferro-cene, rac-(R,RFc)-27.For synthesis see rac-(S,RFc)-27Method B:

The product was obtained as a red solid. Mp: 76-77 �C. 1HNMR (400 MHz, CDCl3): δ 1.10 (t, J = 7.4 Hz, 3H, CH3),2.34-2.60 (m, 3H, CHAHB þ OH), 4.12 (bs, 6H, Cp0 þ H4),4.16-4.22 (m,1H,H5), 4.26-4.32 (m, 1H,H3), 5.89 (d,J=2.1Hz,1H,H6), 7.11-7.18 (m, 1H,H10), 7.31-7.38 (m, 1H,H11), 7.56(dd, J=8.0Hz, J=0.9Hz, 1H, H9), 7.69 (dd, J=7.8Hz, J=1.5Hz, 1H,H12). 13C{1H}NMR(100.6MHz,CDCl3):δ 14.6 (s,CH3), 21.0 (s, CHAHB), 66.4 (s, C4), 68.4 (s, C5), 68.9 (s, C3),69.4 (s, Cp0), 71.2 (s, C6), 89.9 (s, C1 þ C2), 122.8 (s, C8), 127.3(s, C11), 128.8 (s, C12), 128.9 (s, C10), 132.9 (s, C9), 141.7 (s,C7). HR-MS (EI, 30 �C): m/z = [M]þ calcd 397.9970 forC19H19BrFeO, found 397.9960.

rac-2-Ethylferrocenylcarbaldehyde, rac-28. A solution of rac-26 (2.00 g, 6.826 mmol) in THF (10 mL) was degassed andcooled to -78 �C. Addition of a 1.6 M solution of n-BuLi inhexane (4.69 mL, 7.509 mmol) led to the precipitation of ayellow solid. After stirring for 30 min, DMF (1.00 mL) wasadded dropwise, and the mixture was warmed to rt. Stirring wascontinued for an additional 1 h, and the reaction was quenchedby the addition of water. The product was extracted with DEE(2 � 50 mL), the combined organic layers were washed withwater and brine, and the solvent was removed under reducedpressure. Chromatography on aluminum oxide 90 using PE/EA=7:3 as eluent afforded the title compound as a red oil (1.537 g,6.348 mmol, 93% yield). 1HNMR (400MHz, CDCl3): δ 1.21 (t,J=7.5 Hz, 3H, CH3), 2.58-2.76 (m, 2H, CHAHB), 4.21 (s, 5H,Cp0), 4.46-4.49 (m, 1H,H4), 4.50-4.53 (m, 1H,H5), 4.70-4.73(m, 1H, H3), 10.09 (s, 1H, CHO). 13C{1H} NMR (100.6 MHz,CDCl3): δ 15.3 (s, CH3), 21.1 (s, CHAHB), 69.8 (s, C3), 70.0 (s,Cp0), 71.0 (s, C4), 73.0 (s, C5), 76.5 (s, C2), 94.0 (s, C1), 193.7 (s,CHO). HR-MS (EI, 30 �C): m/z = [M]þ calcd 242.0394 forC13H14FeO, found 242.0389.

rac-(S,RFc)-1-Ethyl-2-(r-methoxy-2-bromophenylmethyl)ferro-cene, rac-(S,RFc)-29.The compoundwas obtained starting fromrac-(S,RFc)-27 (2.00 g, 5.011mmol) following general procedureB. Purification involved chromatography on aluminum oxide90 using PE/EA = 20:1 as eluent to give the title compound asan orange-red oil (1.428 g, 3.457 mmol, 69% yield). 1H NMR(400 MHz, CDCl3): δ 0.94 (t, J= 7.5 Hz, 3H, CH3), 2.14-2.26(m, 1H, CHAHB), 2.37-2.49 (m, 1H, CHAHB), 3.42 (s, 3H,OCH3), 3.97-4.02 (m, 1H, H4), 4.03-4.07 (m, 1H, H5),4.09-4.14 (m, 1H, H3), 4.17 (s, 5H, Cp0), 5.57 (s, 1H, H6),7.07-7.12 (m, 1H,H10), 7.24-7.30 (m, 1H, H11), 7.38 (dd, J=7.8 Hz, J=1.8 Hz, 1H, H12), 7.50 (dd, J=8.0 Hz, J=1.2 Hz,1H, H9). 13C{1H} NMR (100.6 MHz, CDCl3): δ 14.1 (s, CH3),21.0 (s, CHAHB), 56.9 (s, OCH3), 65.1 (s, C4), 66.8 (s, C3), 67.4(s, C5), 69.3 (s, Cp0), 79.2 (s, C6), 88.5 (s, C1/C2), 88.9 (s, C1/C2),124.1 (s, C8), 127.8 (s, C11), 129.0 (s, C10), 129.6 (s, C12), 132.2(s, C9), 140.0 (s, C7). HR-MS (EI, 30 �C): m/z = [M]þ calcd412.0127 for C20H21BrFeO, found 412.0122.

rac-(R,RFc)-1-Ethyl-2-8r-methoxy-2-bromophenylmethyl)ferro-cene, rac-(R,RFc)-29. The complex was obtained starting fromrac-(R,RFc)-27 (2.00 g, 5.011mmol) following general procedureB. Purification involved chromatography on aluminum oxide90 using PE/EA = 20:1 as eluent to give the title compound asan orange-red oil (1.364 g, 3.302 mmol, 66% yield). 1H NMR(400 MHz, CDCl3): δ 1.24 (t, J= 7.5 Hz, 3H, CH3), 2.53-2.60(m, 2H, CHAHB), 3.20 (s, 3H, OCH3), 3.90 (s, Cp’), 4.01-4.03


(m, 1H, H3), 4.04-4.08 (m, 1H, H4), 4.15-4.19 (m, 1H, H5),5.64 (s, 1H, H6), 7.18-7.24 (m, 1H, H10), 7.38-7.44 (m, 1H,H11), 7.62-7.68 (m, 2H, H9 þ H12). 13C{1H} NMR (100.6MHz, CDCl3): δ 14.7 (s, CH3), 21.0 (s, CH

AHB), 56.6 (s, OCH3),66.3 (s, C3), 66.4 (s, C4), 67.9 (s, C5), 69.1 (s, Cp0), 79.1 (s, C6),85.9 (s, C2), 90.2 (s, C1), 124.2 (s, C8), 127.5 (s, C11), 129.1 (s,C10), 129.3 (s, C12), 132.5 (s, C9), 140.6 (s, C7). HR-MS (EI,30 �C): m/z = [M]þ calcd 412.0127 for C20H21BrFeO, found412.0118.(S,SFc)-1-Trimethylsilyl-2-(r-hydroxy-2-bromophenylmethyl)-

ferrocene, (S,SFc)-31. A 1.3 M solution of isopropylmagnesiumchloride/lithium chloride complex in THF (60 mL, 78.00 mmol)was cooled to -15 �C, and 1,2-dibromobenzene (18.40 g, 78.00mmol) was added dropwise. Stirring was continued for 2 h at-15 �C followed by the slow addition of a solution of aldehyde(SFc)-30 (15.04 g, 52.55 mmol) in THF (60 mL). After completeaddition, stirring was continued for 30min at-15 �Cand for 1 hat rt. The reactionmixture was quenched by the careful additionof saturated aqueous ammonium chloride solution, and THFwas removed on a rotary evaporator. The residue was extractedwith DEE (2 � 300 mL), and the combined organic layers werewashed with water and brine and dried over MgSO4. Chro-matography on aluminum oxide 90 using PE/EA = 20:1 aseluent afforded the productwith an ee>90%.Recrystallizationfromheptane gave the pure product as a red oil with ee>99.8%(13.95 g, 31.46 mmol, 60% yield). 1HNMR (400MHz, CDCl3):δ 0.13 (s, 9H, Si(CH3)3), 2.56 (d, J = 3.9 Hz, 1H, OH),4.17-4.19 (m, 1H, H2), 4.26 (s, 5H, Cp’), 4.38 (t, J = 2.3 Hz,1H, H3), 4.43-4.45 (m, 1H, H4), 5.85 (d, J= 3.9 Hz, 1H, H6),7.08-7.14 (m, 1H, H10), 7.18-7.22 (m, 2H, H11 þ H12), 7.53(d, J=8.0Hz, 1H, H9). 13C{1H}NMR (100.6MHz, CDCl3): δ0.1 (s, Si(CH3)3), 68.7 (s, Cp

0), 69.6 (s, C3), 70.3 (s, C4), 70.7 (s,C6), 70.9 (s, C1), 74.9 (s, C2), 97.3 (s, C5), 123.9 (s, C8), 127.3 (s,C11), 129.6 (s, C10þ C12), 132.7 (s, C9), 142.3 (s, C7). HR-MS(ESI in MeOH/MeCN): m/z = [M]þ calcd 442.0053 forC20H23BrFeOSi, found 442.0059. [R]20λ (nm): þ56.5 (589),þ61.5 (578), þ85.8 (546) (c 0.660, CH2Cl2). HPLC (OD-H,8% i-PrOH, 0.6 mL/min, 254 nm): tr/min = 8.4 (S,SFc), 10.4(R,RFc).(S,SFc)-1-Trimethylsilyl-2-(r-methoxy-2-bromophenylmethyl)-

ferrocene, (S,SFc)-32. The complex was obtained starting from(S,SFc)-31 (13.95 g, 31.46 mmol) following general procedure B.Purification involved chromatography on aluminum oxide 90using PE/EA=40:1 as eluent to give the title compound as a redsolid (13.40 g, 29.30 mmol, 93% yield). Mp: 88 �C. 1H NMR(400MHz,CDCl3): δ 0.16 (s, 9H, Si(CH3)3), 3.55 (s, 3H,OCH3),4.12-4.14 (m, 1H, H2), 4.14-4.16 (m, 1H, H4), 4.20 (s, 5H,Cp0), 4.27 (t, J = 2.3 Hz, 1H, H3), 5.42 (s, 1H, H6), 7.10-7.16(m, 1H, H10), 7.25-7.30 (m, 2H, H11, H12), 7.54 (d, J = 8.0,1H, H9). 13C{1H} NMR (100.6 MHz, CDCl3): δ 0.2 (s, Si-(CH3)3), 57.7 (s, OCH3), 68.9 (s, Cp0), 69.0 (s, C3), 69.3 (s, C1),71.3 (s, C4), 74.7 (s, C2), 79.9 (s, C6), 94.5 (s, C5), 124.3 (s, C8),127.3 (s, C11), 129.1 (s, C10), 129.7 (s, C12), 132.5 (s, C9), 141.2(s, C7). HR-MS (ESI in MeOH/MeCN): m/z = [M]þ calcd456.0209 for C21H25BrFeOSi, found 456.0215. [R]20λ (nm):þ109.1 (589), þ117.7 (578), þ163.9 (546) (c 0.894, CH2Cl2).rac-(R,SFc)-1-Bromo-2-[r-(diphenylphosphino-KP)phenylmethyl]-

ferrocene Trihydridoboron, rac-(R,SFc)-33(BH3). This com-pound was obtained starting from rac-(R,SFc)-20 (200 mg,0.5194 mmol) following general procedure A (80 �C, 18 h).Purification involved chromatography on aluminum oxide 90using PE/DEE= 4:1f 2:1 as eluent to give the title compoundas a yellow foam (216 mg, 0.3906 mmol, 75% yield). Mp:153-154 �C (dec). 1H NMR (400 MHz, CDCl3): δ 0.60-1.65(bs, 3H, BH3), 3.61 (s, 5H, Cp0), 4.18-4.21 (m, 1H, H3), 4.24-4.28 (m, 1H, H2), 4.76-4.81 (m, 1H, H4), 4.80 (d, J= 17.2 Hz,1H, H6), 7.17-7.25 (m, 3H, PhB-meta þ PhC-para), 7.28-7.42(m, 7H, PhA-meta þ PhB-ortho þ PhC-meta þ PhB-para),7.41-7.47 (m, 1H, PhA-para), 7.53-7.61 (m, 2H, PhC-ortho),7.72-7.80 (m, 2H, PhA-ortho). 13C{1H} NMR (100.6 MHz,

CDCl3):δ42.6 (d,J=28.0Hz,C6), 67.0 (s,C3), 67.6 (d,J=2.9Hz,C4), 68.3 (s, C2), 71.2 (s, Cp0), 82.1 (d, J = 4.0 Hz, C1/C5),86.0 (d, J = 6.7 Hz, C1/C5), 127.42 (d, J = 2.0 Hz, PhC-para),127.44 (d, J = 52.8 Hz, PhA/B-ipso), 127.8 (s, PhC-meta), 127.9(d, J = 9.5 Hz, PhB-meta), 128.4 (d, J = 9.8 Hz, PhA-meta),130.6 (d, J = 5.3 Hz, PhC-ortho), 130.8 (d, J = 2.5 Hz,PhB-para), 131.3 (d, J = 2.3 Hz, PhA-para), 133.2 (d, J = 8.5Hz, PhB-ortho), 133.5 (d, J= 8.4 Hz, PhA-ortho), 138.8 (d, J=1.6 Hz, PhC-ipso). PhA/B-ipso not observed. 31P NMR (162MHz, CDCl3): δ 26.9 (bs). HR-MS (ESI in MeOH/MeCN):m/z=[M]þ calcd 552.0484 for C29H27BBrFeP, found 552.0475.

rac-(S,SFc)-1-Bromo-2-[r-(diphenylphosphino-KP)phenylmethyl]-ferrocene Trihydridoboron, rac-(S,SFc)-33(BH3). This compoundwas obtained starting from rac-(S,SFc)-20 (200 mg, 0.5194 mmol)following general procedure A (80 �C, 18 h). Purification involvedcrystallization three times fromEA to give the compoundas orangecrystals suitable for X-ray diffraction (156 mg, 0.2821 mmol, 54%yield). Mp: 185-187 �C (dec). 1H NMR (400 MHz, CDCl3): δ0.70-2.03 (bs, 3H,BH3), 3.78 (s, 5H,Cp0), 4.19-4.23 (m, 1H,H3),4.36-4.42 (m, 1H, H2), 4.97-5.03 (m, 1H, H4), 5.13 (d, J= 16.9Hz, 1H,H6), 6.90-6.98 (m, 3H, PhC-metaþ PhC-para), 7.00-7.12(m, 4H, PhB-meta þ PhC-ortho), 7.15 7.23 (m, 1H, PhB-para),7.23-7.30 (m, 2H, PhB-ortho), 7.61-7.74 (m, 3H, PhA-meta þPhA-para), 8.33-8.42 (m, 2H, PhA-ortho). 13C{1H} NMR (100.6MHz,CDCl3):δ41.6 (d,J=32.7Hz,C6), 66.3 (s,C3), 67.7 (s,C4),69.1 (s, C2), 71.6 (s, Cp0), 80.3 (d, J = 11.6 Hz, C1/C5), 85.9 (d,J = 5.9 Hz, C1/C5), 126.6 (d, J = 2.2 Hz, PhC-para), 127.68 (bs,PhC-meta), 127.73 (d,J=9.6Hz,Ph-Bmeta), 128.8 (d,J=52.4Hz,PhA-ipso), 129.2 (d, J= 9.5 Hz, PhA-meta), 129.6 (d, J= 4.3 Hz,PhC-ortho), 130.3 (d, J=2.2 Hz, PhB-para), 131.9 (d, J=2.2 Hz,PhA-para), 132.7 (d, J=8.2 Hz, PhB-ortho), 133.3 (d, J=8.4 Hz,PhA-ortho), 137.8 (s, PhC-ipso). PhB-ipso not observed. PhA andPhB connected to P. 31P NMR (162 MHz, CDCl3): δ 21.0 (bs).HR-MS (ESI in MeOH/MeCN): m/z = [M]þ calcd 552.0484 forC29H27BBrFeP, found 552.0480.

rac-(R,SFc)-1-Diphenylphosphino-2-[r-(diphenylphosphino-KP)-phenylmethyl]ferrocene Trihydridoboron, rac-(R,SFc)-34(BH3).This compoundwas obtained starting from rac-(R,SFc)-21 (200mg, 0.4081 mmol) following general procedure A (80 �C, 18 h).Purification involved chromatography on aluminum oxide 90usingPE/DEE=4:1f 2:1 as eluent to give the title compoundasa yellow foam (175 mg, 0.2659 mmol, 65% yield). Mp: 102-104 �C. NMR data were in accordance with those reported inref 16.

rac-(S,SFc)-1-Diphenylphosphino-2-[r-(diphenylphosphino-KP)-phenylmethyl]ferrocene Trihydridoboron, rac-(S,SFc)-34(BH3).This compound was obtained starting from rac-(S,SFc)-21(500 mg, 1.020 mmol) following general procedure A (80 �C,18 h). Purification involved crystallization twice fromEA to givethe compound as orange crystals (389 mg, 0.5787 mmol, 57%yield). Mp: >230 �C (dec). 1H NMR (400 MHz, CDCl3): δ0.74-2.42 (bs, 6H, 2 � BH3), 3.67 (s, 5H, Cp0), 3.72-3.75 (m,1H, H4), 4.51-4.55 (m, 1H, H3), 5.71-5.75 (m, 1H, H2), 5.77(d, J=17.5Hz, 1H,H6), 5.70-7.30 (bs, 4H, Ph), 6.55-6.64 (m,1H, Ph), 6.75-6.84 (m, 4H, Ph), 6.90-6.98 (m, 2H, Ph),7.00-7.10 (m, 2H, Ph), 7.10-7.18 (m, 2H, Ph), 7.35-7.42 (m,2H, Ph), 7.43-7.49 (m, 1H, Ph), 7.50-7.60 (m, 2H, Ph),7.63-7.70 (m, 1H, Ph), 7.72-7.80 (m, 2H, Ph), 8.64-8.74 (m,2H, Ph). 13C{1H} NMR (100.6 MHz, CDCl3): δ 39.9 (d, J =30.8 Hz, C6), 67.7 (dd, J = 64.9 Hz, J = 10.9 Hz, C1), 70.7 (s,Cp0), 70.8 (d, J=6.4 Hz, C3), 72.8 (d, J=3.2 Hz, C4), 74.2 (d,J= 7.0 Hz, C2), 91.9 (dd, J= 15.2 Hz, J= 5.3 Hz, C5), 125.9(d, J = 2.7 Hz, Ph-para), 126.9 (bs, Ph-ortho/meta), 127.5 (d,J=9.9Hz, Ph-meta), 127.7 (d, J=10.2Hz, Ph-meta), 128.1 (d,J=10.3Hz, Ph-meta), 128.5 (d, J=49.7Hz, Ph-ipso), 129.0 (d,J = 55.8 Hz, Ph-ipso), 129.0-129.5 (bs, Ph-ortho/meta), 129.1(d, J= 9.8 Hz, Ph-meta), 129.8 (d, J= 2.3 Hz, Ph-para), 129.9(d, J= 2.2 Hz, Ph-para), 130.6 (d, J= 58.6 Hz, Ph-ipso), 130.7(d, J= 59.7 Hz, Ph-ipso), 131.0 (d, J= 2.4 Hz, Ph-para), 131.8(d, J= 9.1 Hz, Ph-ortho), 132.0 (d, J= 2.3 Hz, Ph-para), 132.4


(d, J = 8.2 Hz, Ph-ortho), 133.4 (d, J = 9.9 Hz, Ph-ortho),134.4 (d, J = 8.5 Hz, Ph-ortho), 137.4 (s, Ph-ipso). 31P NMR(162 MHz, CDCl3): δ 13.3 (bs, C1-P), 22.6 (bs, C6-P). HR-MS(ESI in MeOH/MeCN): m/z = [M]þ calcd 672.2156 forC41H40B2FeP2, found 672.2161.rac-(R,SFc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)-

phenylmethyl]ferrocene trihydridoboron, rac-(R,SFc)-35(BH3).This compound was obtained starting from rac-(R,SFc)-22(200 mg, 0.5289 mmol) following general procedure A (60 �C,24 h). Purification involved chromatography on aluminumoxide 90 using PE/DEE= 10/:1f 2:1 as eluent to give the titlecompound as a yellow foam (196 mg, 0.3589 mmol, 68% yield).Mp: 65-66 �C. NMR data were in accordance with thosereported in ref 16.rac-(S,SFc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)phe-

nylmethyl]ferrocene Trihydridoboron, rac-(S,SFc)-35(BH3). Thiscompound was obtained starting from rac-(S,SFc)-22 (700 mg,1.850 mmol) following general procedure A (60 �C, 24 h).Attempts to purify this compound were unsuccessful, but thedesired product could be identified by NMR spectroscopy. 1HNMR (400 MHz, CDCl3): δ -0.06 (s, 9H, C(CH3)3), 0.62-1.91 (bs, 3H, BH3), 3.79 (s, 5H, Cp0), 3.99-4.02 (m, 1H, H2),4.39-4.43 (m, 1H, H3), 4.99 (d, J = 15.4 Hz, 1H, H6), 5.20-5.24 (m, 1H, H4), 6.58-6.65 (m, 2H, PhC-ortho), 6.85-6.92 (m,2H, PhC-meta), 6.93-7.00 (m, 1H, PhC-para), 7.06-7.27 (m,5H, PhB-ortho þ PhB-meta þ PhB-para), 7.58-7.68 (m, 3H,PhA-metaþ PhA-para), 8.19-8.27 (m, 2H, PhA-ortho). 13C{1H}NMR (100.6 MHz, CDCl3): δ 0.1 (s, C(CH3)3), 45.2 (d, J = 27.5Hz,C6), 69.3 (s, Cp0), 70.1 (s, C3), 70.5 (d, J=10.7Hz, C1), 73.4(d, J=3.9 Hz, C4), 74.0 (s, C2), 92.1 (d, J=4.2 Hz, C5), 126.5(d, J = 2.5 Hz, PhC-para), 127.4 (d, J = 2.1 Hz, PhC-meta),127.7 (d, J = 9.7 Hz, PhB-meta), 128.7 (d, J = 50.1 Hz,PhA-ipso), 128.9 (d, J = 9.5 Hz, PhA-meta), 129.2 (d, J =54.4 Hz, PhB-ipso), 130.1 (d, J = 3.8 Hz, PhC-ortho), 130.4 (d,J=2.2Hz, PhB-para), 131.7 (d, J=2.3Hz, PhA-para), 133.2 (d,J= 7.6 Hz, PhB-ortho), 133.7 (d, J=8.3 Hz, PhA-ortho), 139.2(d, J= 2.2 Hz, PhC-ipso). 31P NMR (162 MHz, CDCl3): δ 22.9(bs). PhA and PhB connected to P.(R,RFc)-1-Diphenylphosphino-2-(1-diphenylphosphinoethyl)ferro-

cene, (R,RFc)-36a. To a solution of (R,RFc)-11 (1.55 g, 3.512mmol) in distilled and degassed acetic acid (20 mL) was addeddiphenylphosphine (785 mg, 4.215 mmol), and the resultingmixture was degassed three times. After heating to 80 �C over-night, the solvent was removed under reduced pressure and theremaining yellow solid was redissolved in aminimum amount ofDCM. An aliquot was analyzed by 1HNMR, and this indicatedfull conversion and complete retention of configuration. Thesolvent was again removed under reduced pressure, and thecrude product was chromatographed under inert conditions onaluminum oxide 90 using PE/EA = 1:0 f 20:1 as eluent. Thepure compound was obtained as a yellow foam (1.81 g, 3.108mmol, 88%yield).Mp: 54-64 �C. 1HNMR(400MHz,CDCl3):δ 1.10 (dd, J=9.7Hz, J=7.2Hz, 3H, CHCH3), 3.65-3.79 (m,1H, CHCH3), 3.86 (s, 5H, Cp0), 3.85-3.88 (m, 1H, H5),4.23-4.27 (m, 2H, H3 þ H4), 7.20-7.25 (m, 5H, PhD-ortho þPhD-meta þ PhD-para), 7.28-7.35 (m, 4H, PhB-meta þPhB-para þ PhC-para), 7.36-7.42 (m, 5H, PhA-meta þ PhC-meta þ PhA-para), 7.48-7.55 (m, 2H, PhB-ortho), 7.56-7.67(m, 4H, PhA-ortho þ PhC-ortho). 13C{1H} NMR (100.6 MHz,CDCl3): δ 22.1 (dd, J=9.1 Hz, J=6.1 Hz, CHCH3), 30.3 (dd,J=15.4 Hz, J=7.4 Hz,CHCH3), 69.3 (s, C4), 69.8 (d, J=1.4Hz, Cp0), 70.7-70.8 (m, C5), 71.1 (dd, J= 7.5 Hz, J= 4.6 Hz,C3), 74.5 (dd, J = 9.8 Hz, J = 5.5 Hz, C1), 99.3 (dd, J =26.1 Hz, J = 18.2 Hz, C2), 127.7 (s, 1C, Ph), 127.8-128.3 (m,9C, Ph), 128.8 (s, 1C, Ph), 129.0 (s, 1C, Ph), 132.6 (d, J = 18.0Hz, PhD-ortho), 133.1 (dd, J=18.1Hz, J=2.0Hz, PhC-ortho),134.9 (d, J = 20.9 Hz, PhB-ortho), 135.2 (d, J = 21.6 Hz,PhA-ortho), 138.2 (d, J = 19.4 Hz, Ph-ipso), 138.4 (d, J =9.0 Hz, Ph-ipso), 139.0 (d, J= 15.0 Hz, Ph-ipso), 140.4 (d, J =9.0 Hz, Ph-ipso). PhA þ PhD connected to C1-P, PhB þ PhC

connected to C2-CH-P. 31P NMR (162 MHz, CDCl3): δ -23.4(d, J = 9.8 Hz, C1-P), 0.6 (d, J = 9.8 Hz, C2-CH-P). HR-MS(ESI in MeOH/MeCN): m/z = [M þ Hþ]þ calcd 583.1407 forC36H33FeP2, found 583.1399. [R]20λ (nm):þ295.8 (589),þ319.6(578), þ416.8 (546) (c 0.935, CHCl3).

(R,RFc)-1-Diphenylphosphino-2-(1-dicyclohexylphosphinoethyl)-ferrocene, (R,RFc)-36b.To a solution of (R,RFc)-11 (2.00 g, 4.532mmol) in distilled and degassed acetic acid (20 mL) was addeddicyclohexylphosphine (1.08 g, 5.438 mmol), and the resultingmixture was degassed three times. After heating to 80 �C over-night, the solvent was removed under reduced pressure and theremaining yellow solid redissolved in a minimum amount ofDCM. An aliquot was analyzed by 1H NMR, which indicatedfull conversion and complete retention of configuration. Thesolvent was again removed under reduced pressure, and thecrude product was chromatographed under inert conditions onaluminum oxide 90 using PE/EA = 20:1 as eluent. The purecompound was obtained as a yellow foam (2.57 g, 4.323 mmol,95% yield). Mp: 53-57 �C. 1H NMR (400 MHz, CDCl3): δ1.15-1.48 (m, 11H, Cy), 1.23 (dd, J= 7.3 Hz, J= 5.7 Hz, 3H,CHCH3), 1.63-1.95 (m, 11H, Cy), 3.11-3.21 (m, 1H, CHCH3),3.89-3.93 (m, 1H, H5), 3.98 (s, 5H, Cp0), 4.27-4.31 (m, 1H,H4), 4.36-4.39 (m, 1H, H3), 7.16-7.25 (m, 5H, PhB-ortho þPhB-meta þ PhB-para), 7.34-7.40 (m, 3H, PhA-meta þ PhA-para), 7.55-7.63 (m, 2H, PhA-ortho). 13C{1H} NMR (100.6MHz, CDCl3): δ 21.5 (d, J = 7.3 Hz, CHCH3), 26.4-26.8 (m,CHCH3þCy), 27.3-27.9 (m, Cy), 29.2 (d, J=6.9Hz, Cy), 30.0(d, J=9.8 Hz, Cy), 31.1-31.5 (m, Cy), 33.1-33.6 (m, Cy), 69.2(s, C4), 69.7 (d, J= 2.1 Hz, Cp’), 71.3 (dd, J= 4.4 Hz, J= 1.5Hz, C5), 71.9 (dd, J = 10.8 Hz, J = 4.7 Hz, C3), 73.9 (dd, J =10.6 Hz, J= 5.9 Hz, C1), 101.6 (dd, J= 26.5 Hz, J= 18.1 Hz,C2), 127.4 (s, PhB-para), 127.8 (d, J=5.9Hz, PhA/B-meta), 127.9(d, J = 8.0 Hz, PhA/B-meta), 129.0 (s, PhA-para), 132.4 (d, J =17.5 Hz, PhB-ortho), 135.4 (d, J=22.1 Hz, PhA-ortho), 138.7 (d,J=8.9Hz, PhA-ipso), 141.1 (d, J=8.8Hz, PhB-ipso). 31PNMR(162MHz,CDCl3): δ-24.3 (d, J=8.5Hz,PPh2), 9.0 (d, J=8.5Hz, PCy2). HR-MS (ESI in MeOH/MeCN): m/z = [M þ Hþ]þ

calcd 595.2347 for C36H45FeP2, found 595.2354. [R]20λ (nm):þ327.1 (589), þ353.0 (578), þ462.8 (546) (c 0.836, CHCl3).

(R,RFc)-1-(Diphenylphosphino-KP)-2-[1-(di-tert-butylphosphino-KP)ethyl]ferrocene Hexahydridodiboron, (R,RFc)-36c(BH3)2. Toa solution of (R,RFc)-11 (2.00 g, 4.532 mmol) in distilled anddegassed acetic acid (20 mL) was added di-tert-butylphosphine(795 mg, 5.438 mmol), and the resulting mixture was degassedthree times. After heating to 80 �C overnight, the solvent wasremoved under reduced pressure and the remaining yellow solidwas redissolved in aminimum amount of DCM.An aliquot wasanalyzed by 1H NMR, and this indicated full conversion andretention of configuration with de = 84%. The solvent wasagain removed under reduced pressure, and a solution of boranein THFwas added (1.0M, 22.66mL, 22.66mmol). After stirringat rt for 4 h, water was added dropwise to quench the excessborane and the solution was extracted with EA. The combinedorganic layers were washed with water and brine and dried overMgSO4, and the solvents were removed on a rotary evaporator.The pure product was crystallized from EA as orange crystals(896 mg, 1.572 mmol, 35% yield). Mp: 192-196 �C (dec). 1HNMR (400 MHz, CDCl3): δ 0.32-2.13 (bs, 6H, 2 � BH3), 1.28(dd, J=9.5Hz, J=7.4Hz, 3H, CHCH3), 1.38 (d, J=12.4Hz,9H, CB(CH3)3), 1.45 (d, J=12.4Hz, 9H, CA(CH3)3), 4.01-4.05(m, 1H, H5), 4.03-4.14 (m, 1H, CHCH3), 4.13 (s, 5H, Cp0),4.47-4.50 (m, 1H, H4), 5.03-5.07 (m, 1H, H3), 7.33-7.51 (m,6H, PhA-metaþ PhA-para þ PhB-metaþ PhB-para), 7.55-7.65(m, 2H, PhB-ortho), 7.70-7.80 (m, 2H, PhA-ortho). 13C{1H}NMR (100.6 MHz, CDCl3): δ 26.0 (d, J = 5.4 Hz, CHCH3),28.2 (d, J = 24.3 Hz, CHCH3), 28.4 (s, CA(CH3)3), 30.1 (s,CB(CH3)3), 35.1 (d, J=20.7 Hz,CA/B(CH3)3), 35.2 (d, J=27.6Hz, CA/B(CH3)3), 63.0 (dd, J=62.8 Hz, J=10.5 Hz, C1), 70.0(d, J= 6.5 Hz, C4), 70.1 (s, Cp0), 72.3 (d, J= 2.7 Hz, C5), 75.1(d,J=6.3Hz,C3), 98.8 (d,J=14.9Hz,C2), 128.1 (d,J=10.1Hz,


PhA-meta), 128.4 (d, J = 9.9 Hz, PhB-meta), 130.6 (d, J =2.2Hz, PhA/B-para), 130.9 (d, J=2.2Hz, PhA/B-para), 131.0 (d,J=62.8Hz, PhA/B-ipso), 132.2 (d, J=9.1Hz, PhB-ortho), 132.6(d, J= 55.6 Hz, PhA/B-ipso), 133.7 (d, J = 9.2 Hz, PhA-ortho).31PNMR(162MHz,CDCl3):δ 13.6 (bs,PPh2), 53.1 (bs,P-t-Bu2).HR-MS (ESI in MeOH/MeCN): m/z = [M þ Naþ]þ calcd593.2520 for C32H46B2FeNaP2, found 593.2506. [R]20λ (nm):þ257.3 (589), þ277.7 (578), þ365.5 (546) (c 0.636, CHCl3).(R,RFc)-1-Diphenylphosphino-2-(1-di-tert-butylphosphinoethyl)-

ferrocene, (R,RFc)-36c. A degassed suspension of (R,RFc)-36c-(BH3)2 (820 mg, 1.438mmol) in morpholine (15mL) was heatedto 100 �C for 3 h. After cooling, the morpholine was removedunder reduced pressure and the residuewas extractedwithDEE.The combined organic layers were washed with degassed 5%aqueous citric acid solution and degassed brine and dried overMgSO4. The solvent was removed on a rotary evaporator, andthe crude product was purified by chromatography under inertconditions on aluminumoxide 90 using PE/DEE=1:1 as eluentto give the title compound as a yellow foam (724 mg, 1.335mmol, 93%yield).Mp: 52-56 �C. 1HNMR(400MHz,CDCl3):δ1.29 (d, J= 11.0 Hz, 9H, CB(CH3)3), 1.30 (dd, J = 7.6 Hz, J =3.0 Hz, 3H, CHCH3), 1.35 (d, J = 10.6 Hz, 9H, CA(CH3)3),3.34-3.44 (m, 1H,CHCH3), 3.89-3.93 (m, 1H,H5), 3.98 (s, 5H,Cp0), 4.31-4.34 (m, 1H,H4), 4.52-4.56 (m, 1H,H3), 7.19-7.26(m, 5H, PhB-orthoþ PhB-metaþ PhB-para), 7.34-7.40 (m, 3H,PhA-metaþ PhA-para), 7.54-7.63 (m, 2H, PhA-ortho). 13C{1H}NMR (100.6MHz, CDCl3): δ 23.2 (dd, J=6.1 Hz, J=2.9 Hz,CHCH3), 29.9 (dd, J= 31.4 Hz, J= 9.6 Hz, CHCH3), 30.7 (d,J = 13.5 Hz, CA(CH3)3), 31.9 (d, J = 14.9 Hz, CB(CH3)3),33.0 (d, J = 32.2 Hz, CA/B(CH3)3), 33.7 (d, J = 23.9 Hz,CA/B(CH3)3), 69.4 (s, C4), 69.9 (d, J = 2.9 Hz, Cp0), 70.5 (dd,J= 4.3 Hz, J= 2.5 Hz, C5), 71.1 (dd, J= 9.4 Hz, J= 4.1 Hz,C3), 73.7 (t, J= 8.0 Hz, C1), 103.9 (dd, J= 22.9 Hz, J= 26.2Hz, C2), 127.5 (s, PhB-para), 127.8 (d, J=12.2Hz, PhA/B-meta),127.9 (d, J = 12.2 Hz, PhA/B-meta), 129.0 (s, PhA-para), 132.5(d, J= 17.6 Hz, PhB-ortho), 135.4 (d, J= 22.2 Hz, PhA-ortho),138.7 (d, J=7.9 Hz, PhA-ipso), 141.1 (d, J=8.8 Hz, PhB-ipso).31P NMR (162 MHz, CDCl3): δ -24.5 (s, PPh2), 42.4 (s,P-t-Bu2). HR-MS (ESI in MeOH/MeCN): m/z = [M þ Hþ]þ

calcd 543.2034 forC32H41FeP2, found 543.2026. [R]20λ (nm):þ399.5(589),þ430.6 (578),þ563.4 (546) (c 0.814, CHCl3).Dichloro[(R,SFc)-1-trimethylsilyl-2-(r-diphenylphosphino-

2-(diphenylphosphinophenyl)methyl)ferrocene-P,P]palladium,

[PdCl2((R,SFc)-3a)]. A solution of bis(acetonitrile)dichloro-palladium(II) (25.9 mg, 0.1000 mmol) in DMF (2 mL) wasadded to a solution of (R,SFc)-3a (71.7 mg, 0.1000 mmol) inDMF (2 mL), and the resulting mixture was stirred at rt over-night. The solvent was removed under reduced pressure, and theresidue was dissolved in a minimum amount of chloroform.Careful addition of DEE led to precipitation of a yellow-brownsolid, which was collected by filtration, washed with DEE (2� 2mL), and dried in vacuo (74 mg, 0.0828 mmol, 83% yield). Mp:>230 �C (dec). 1H NMR (600 MHz, CDCl3): δ -0.04 (s, 9H,Si(CH3)3), 3.28 (s, 5H, Cp0), 4.00 (dd, J = 2.5 Hz, J = 1.1 Hz,1H,H2), 4.42 (t, J=2.5Hz, 1H,H3), 4.79 (dd, J=18.2Hz, J=6.3 Hz, 1H, H6), 5.27 (dd, J = 2.5 Hz, J = 1.1 Hz, 1H, H4),6.70-6.75 (m, 2H, PhC-ortho), 6.85-6.90 (m, 2H, PhB-ortho),7.01-7.05 (m, 2H, PhC-meta), 7.12-7.15 (m, 2H, PhB-meta),7.21-7.25 (m, 1H, PhC-para), 7.28-7.34 (m, 3H, H9 þ H10 þPhB-para), 7.36-7.40 (m, 2H, PhD-meta), 7.47-7.65 (m, 1H,PhD-para), 7.58-7.65 (m, 4H, H11 þ PhA-meta þ PhA-para),7.76-7.79 (m, 1H, H12), 7.99-8.04 (m, 2H, PhD-ortho),8.47-8.52 (m, 2H, PhA-ortho). 13C{1H} NMR (150.9 MHz,CDCl3): δ 1.3 (s, Si(CH3)3), 38.6 (dd, J= 29.8 Hz, J= 8.6 Hz,C6), 68.9 (s, Cp0), 71.6 (s, C3), 72.8 (dd, J=6.6 Hz, J=3.3 Hz,C4), 73.9 (d, J = 2.4 Hz, C1), 74.0 (s, C2), 92.2 (d, J = 6.7 Hz,C5), 122.0 (dd, J=48.5Hz, J=14.1Hz, C8), 126.1 (d, J=49.4Hz, PhD-ipso), 127.2 (d, J = 11.7 Hz, PhC-meta), 127.6 (d,J=56.1Hz, PhC-ipso), 128.0 (d, J=7.2Hz, C10), 128.2 (d, J=12.0 Hz, PhB-meta), 128.7 (d, J = 58.1 Hz, PhA-ipso), 128.8

(d, J = 12.0 Hz, PhA-meta), 129.1 (d, J = 10.3 Hz, PhD-meta),130.4 (d, J=3.0Hz, PhB-para), 131.1 (d, J=3.1Hz, PhC-para),131.8 (d, J = 2.3 Hz, PhA-para), 131.9-132.0 (m, C11 þ PhD-para), 132.8 (d, J = 61.5 Hz, PhB-ipso), 132.9 (d, J = 10.2 Hz,PhB-ortho), 134.2-134.4 (m, C12 þ PhC-ortho), 135.2-135.4(m, PhD-ortho), 136.3 (d, J=11.0Hz, PhA-ortho), 137.3 (d, J=2.2 Hz, C9), 148.0 (dd, J=14.4 Hz, J=4.3 Hz, C7). 31P NMR(243 MHz, CDCl3): δ 17.6 (d, J= 20.2 Hz, C8-P), 35.9 (d, J=20.2 Hz, C6-P). PhA þ PhB connected to C8-P, PhC þ PhD

connected to C6-P. Anal. Calcd for C44H42Cl2FeP2PdSi 30.25CHCl3: C, 57.62; H, 4.62. Found: C, 58.01; H, 4.50. ESI-MS (MeOH/MeCN): m/z = 857.2 [M - Cl-]þ. [R]20λ (nm):þ289.8 (589), þ308.6 (578), þ393.1 (546) (c 0.554, CH2Cl2).

Dichloro[(R,SFc)-1-trimethylsilyl-2-(r-bis(3,5-bistrifluoromethyl-phenyl)phosphino-2-(diphenylphosphinophenyl)methyl)ferrocene-P,P]palladium, [PdCl2((R,SFc)-3b)]. A solution of bis(acetoni-trile)dichloropalladium(II) (25.9 mg, 0.1000 mmol) in DMF(2 mL) was added to a solution of (R,SFc)-3b (98.9 mg, 0.1000mmol) in DMF (2 mL), and the resulting mixture was stirred atrt overnight. Solvent was then removed under reduced pressure,and the residue was redissolved in a minimum amount ofchloroform. Careful addition of DEE led to precipitation of ared-brown solid, which was collected by filtration, washed withDEE (2� 2mL), and dried in vacuo (106mg, 0.0909mmol, 91%yield). Mp: >230 �C (dec). 1H NMR (600 MHz, CDCl3): δ-0.05 (s, 9H, Si(CH3)3), 3.38 (s, 5H, Cp0), 4.09-4.12 (m, 1H,H2), 4.53-4.57 (m, 1H, H3), 4.81 (dd, J=18.5 Hz, J=5.6 Hz,1H,H6), 5.27-5.30 (m, 1H,H4), 6.86-6.93 (m, 2H, PhA-ortho),7.01-7.24 (bs, 2H, PhC-ortho), 7.16-7.22 (m, 2H, PhA-meta),7.33-7.41 (m, 2H, H9 þ PhA-para), 7.43-7.48 (m, 1H, H10),7.61-7.72 (m, 3H, PhB-meta þ PhB-para), 7.72-7.77 (m, 1H,H11), 7.78-7.83 (m, 2H, H12 þ PhC-para), 8.03 (bs, 1H,PhD-para), 8.32-8.38 (m, 2H, PhB-ortho), 8.30-8.47 (bs, 2H,PhD-ortho). 13C{1H} NMR (150.9 MHz, CDCl3): δ 1.1 (s,Si(CH3)3), 39.1 (dd, J=28.5 Hz, J=8.0 Hz, C6), 69.3 (s, Cp0),72.3 (dd, J= 7.4 Hz, J= 2.6 Hz, C4), 72.4 (s, C3), 73.5 (d, J=2.3Hz, C1), 75.2 (s, C2), 90.6 (d, J=7.2Hz, C5), 121.6 (dd, J=48.1 Hz, J= 14.4 Hz, C8), 122.2 (q, J= 274.0 Hz, CF3), 122.5(q, J = 274.0 Hz, CF3), 125.5 (bs, PhC-para), 126.3 (bs,PhD-para), 126.6 (d, J = 58.6 Hz, PhB-ipso), 128.7 (d, J =11.9 Hz, PhA-meta), 129.1 (d, J = 45.1 Hz, PhC/D-ipso), 129.15(s, C10), 129.16 (d, J=11.9Hz, PhB-meta), 130.5-131.1 (m, 2�C-CF3), 130.8 (d, J=30.8Hz, PhC/D-ipso), 131.2 (d, J=33.2Hz,PhA-ipso), 131.3 (d, J=3.1Hz, PhA-para), 132.4 (d, J=2.9Hz,PhB-para), 132.7 (d, J = 10.9 Hz, PhA-ortho), 132.9 (s, C11),133.9-134.1 (m, PhD-ortho þ C12), 135.7 (d, J = 10.4 Hz,PhB-ortho), 137.9 (d, J = 2.6 Hz, C9), 146.0 (dd, J = 14.4 Hz,J= 5.5 Hz, C7), PhC-ortho not observed. 31P NMR (243MHz,CDCl3): δ 18.1 (d, J = 21.1 Hz, C8-P), 33.3 (d, J = 21.1 Hz,C6-P). PhA þ PhB connected to C8-P, PhC þ PhD connected toC6-P. Anal. Calcd for C48H38Cl2F12FeP2PdSi 3 0.25CHCl3: C,48.51; H, 3.23. Found: C, 48.55; H, 3.03. ESI-MS (MeOH/MeCN): m/z = 1164.0 [M]þ. [R]20λ (nm): þ211.3 (589), þ225.8(578), þ290.3 (546) (c 0.062, CH2Cl2).

X-ray Crystallography. X-ray data for the compounds rac-(R,RFc)-2, [PdCl2(R,SFc)-3b], rac-(S,RFc)-7, rac-(S,SFc)-31, andrac-(S,SFc)-33 were collected on two Bruker CCD area detec-tor diffractometers (Smart APEX and Kappa APEX-2) usinggraphite-monochromated Mo KR radiation (λ = 0.71073 A)and combinations of j- and ω-scan frames. All measurementswere carried out at T = 100 K. After data integration with theprogram SAINT, corrections for absorption and λ/2 effects wereappliedwith the programSADABS.22 The structureswere solvedwith the program SHELXS97 and direct methods, and refine-ment on F2 was carried out with the program SHELXL97.23

(22) Bruker programs: SMART, version 2008; APEX2, version 2009.9-0;SAINT, versions 6.45A and 7.68A; SADABS, version 2008/1; SHELXTL,version 2008/4 (Bruker AXS Inc.: Madison, WI).

(23) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122.


Non-hydrogen atoms were refined anisotropically. Most Hatoms were placed in calculated positions and thereafter treatedas riding. Important crystallographic data are as follows.

rac-(R,RFc)-2: C43H38FeP2, Mr = 672.52, orange prismsfrom chloroform/hexane, 0.49 � 0.32 � 0.18 mm, monoclinic,space group P21/c, a = 10.1443(2) A, b = 19.3345(4) A, c =17.0532(3) A, β=91.735(1)�, V= 3343.20(11) A3, Z=4, μ=0.578 mm-1, dx = 1.336 g cm-3, T = 100 K; 49 959 reflectionscollected (θmax = 30.0�) and merged to 9740 independent data(Rint = 0.023); final R indices (all data): R1 = 0.0371, wR2 =0.0875, 416 parameters.

[PdCl2((R,SFc)-3b)] as the chloroform solvate [PdCl2((R,SFc)-3b)] 3CHCl3: C49H39Cl5F12FeP2PdSi, Mr = 1285.33, orangeplates from chloroform/hexane, 0.37 � 0.24 � 0.08 mm, mono-clinic, space group P21, a= 10.7270(16) A, b= 13.3092(19) A,c=18.395(3) A, β=95.214(2)�,V=2615.3(7) A3,Z=2, μ=1.038 mm-1, dx = 1.632 g cm-3, T = 100 K; 44 338 reflectionscollected (θmax= 30.0�) andmerged to 15 197 independent data(Rint = 0.043); final R indices (all data): R1 = 0.0607, wR2 =0.1138, 644 parameters. Flack absolute structure parameter =-0.022(15). CHCl3 solvent molecule partly vacant, refinedpopulation 68.7(5)%.

rac-(S,RFc)-7: C32H31FeOP, Mr= 518.39, orange plates fromchloroform/hexane, 0.32 � 0.30 � 0.13 mm, monoclinic, spacegroup P21/n, a=8.6582(11) A, b=25.464(3) A, c=11.6474(15) A,β=93.500(2)�,V=2563.2(6) A3,Z=4, μ=0.674 mm-1, dx=1.343 g cm-3,T=100K. 37286 reflections collected (θmax=30.0�)andmerged to 7470 independent data (Rint=0.031); finalR indices(all data): R1 = 0.0403, wR2 = 0.0809, 318 parameters.

rac-(S,SFc)-31: C20H23BrFeOSi,Mr = 443.23, orange prismsfrom heptane, 0.41 � 0.18� 0.16 mm, monoclinic, space groupP21/c, a=13.042(5) A, b= 12.521(5) A, c= 12.697(5) A, β=118.354(5)�, V= 1863.5(12) A3, Z=4, μ=3.022 mm-1, dx =1.580 g cm-3, T = 100 K. 12 717 reflections collected (θmax =28.4�) andmerged to 4614 independent data (Rint=0.041); finalR indices (all data): R1=0.0482, wR2 = 0.0699, 221 param-eters. Hydroxy hydrogen atom fully refined.

rac-(S,SFc)-33: C29H27BBrFeP,Mr=553.05, orange crystalsfrom chloroform/hexane, 0.48 � 0.24 � 0.13 mm, monoclinic,space group P21/c, a = 20.7001(5) A, b = 7.2546(2) A, c=17.2963(5) A, β=107.297(1)�, V=2479.94(12) A3, Z=4, μ=2.300 mm-1, dx=1.481 g cm-3, T=100 K; 23 006 reflectionscollected (θmax = 30.0�) and merged to 7212 independent data(Rint = 0.026); final R indices (all data): R1 = 0.0368, wR2=0.0733, 298 parameters.

Acknowledgment. This work was kindly supported bySOLVIAS AG. The authors thank Manuela Gross forsome preparative help.

Supporting Information Available: Standard ORTEP plotsand standard geometric parameters for crystal structures ofcompounds rac-(R,RFc)-2, [PdCl2((R,SFc)-3b)] 3CHCl3, rac-(S,RFc)-7, rac-(S,SFc)-31, and rac-(S,SFc)-33 as well as completecrystallographic data and technical details in CIF format. Thismaterial is available free of charge via the Internet at http://pubs.acs.org.

Synthesis of Ferrocenyl Diphosphine Ligands: Substitution of α-Methoxy or α-Dimethylamino Groups...

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