1 Homogeneous Gold Catalysis – A Reactivity Perspective Dongxu Shu Tang Research Group 12, 10,...

1

Homogeneous Gold Catalysis – A Homogeneous Gold Catalysis – A

Reactivity PerspectiveReactivity Perspective

Dongxu ShuDongxu Shu

Tang Research GroupTang Research Group

12, 10, 200912, 10, 2009

2

ContentsContents

Relativistic effect and reactivity

π-acidity reactivity

Gold catalyzed coupling reaction

Summary

3

Features of Gold CatalysisFeatures of Gold Catalysis

π-acidity: soft Lewis acid, preferentially activate π-systems

AuI and AuIII

AuI: d10, linear bicoordinate geometry, difficult in asymmetric catalysis

Noβ-H elimination

Reluctant to undergo oxidative addition and reductive elimination

4

Relativistic Effect Relativistic Effect

Lower 6s and 6p, higher 5d

Pyykko, P. et al. Acc. Chem. Res. 1979, 12, 276.

5

Origin of Origin of ππ–acidity and Alkynophilicity–acidity and Alkynophilicity

• π-acidity of R3PAu+

1) lower LUMO

2) poor back donation

• Alkynophilicity

1) kinetic in origin

2) LUMO of alkyne is lower

Hertwig, R. H. et al. J. Phys. Chem. 1996, 100, 12253.

Toste, F. D. et al. Nature. 2007, 446, 395.

ΔG ≈ -10 kcal/mol

AuR3P

AuAu

AuNu faster than AuNu

6

ContentsContents


π-acidity reactivity 1. Alkyne 2. Enyne 3. Propargylic ester 4. Allene


Summary

7

ππ-Acidity-Acidity ReactivityReactivity

RearrangementEliminationNu attack

CyclopropanationC-H insertion

AuR

L

AuLR

Au

Au

Nu E

Nu

Nu

Au

E

Nu

E

Nu

Au

E

8

Carbene or CarbocationCarbene or Carbocation

Fürstner, A. et al. Angew. Chem. Int. Ed. 2009, 48, 2510.

Au Au

O O[(R3P)Au] [NTf2]

O O

AuPPh3

OO

Ph3PAu1

2

3

-78oCNTf2 NTf2

OO

Ph3PAu1

2

3 <7.2 kcal/molOO

Ph3PAu1

2

3

9

Carbene or CarbocationCarbene or Carbocation

Goddard, W. A. Toste, F. D. et al. Nature Chem. 2009, 1, 482.

O

O Ph

Ph

LAuCl, AgSbF6

CD2Cl2 O

O

Ph

Ph

O

O Ph

Ph

LAuCl, AgSbF6

CD2Cl2 O

O

Ph

Ph

Ligand Yield

P(OMe)3 0%P(OPh)3 11%PPh3 52%PMe3 56%NHC 80%

OO

Ph3PAu1

2

3

<7.2 kcal/mol

Au

PMe3

Calculated: 22.5 kcal/mol

Au

PMe3

10

Early ResearchEarly Research

Thomas, C. B. et al. J. Chem. Soc. Perkin Trans. II 1976, 1983.

Teles, J. H. et al. Angew. Chem. Int. Ed. 1998, 37, 1415.

Ph Ph + MeOH

Ph3PAuMeMeSO3H

solvent-free

20-50 0C

OMe

PhPh

TOF: Ph3P (610 h-1) < (MeO)3P (1200 h-1) < (PhO)3P (1500 h-1)

TON: Ph3P (5000) > (PhO)3P (2500)

R1 R2

7 mol% H[AuCl4]

MeOH/H2O, 650C

R1R2

O

+ R1R2

O

+ R1

OMe

R2

+ R1

Cl

R2

AuPh3P MeSO3

AuL X

11Hashmi, A. S. K. et al. Angew. Chem. Int. Ed. 2009, 48, 8247.

Stereoselectivity and RegioselectivityStereoselectivity and Regioselectivity

Au

Nu

Au

Nu

antiStereoselectivity

R

AuAuR

Au

RRegioselectivity

•

Au AuAu

HN

OPh

R

Au

R = H5-exo-dig

R = H6-endo-dig

O

NPh

O

NPh

R

Au(IPr)

Can be isolated

O

NPh

R

HH

C Hg

12

ContentsContents




Summary

13

Reactivity Pattern of EnyneReactivity Pattern of Enyne

Furstner, A. et al. Angew. Chem. Int. Ed. 2008, 47, 5030.

Au

Au Au

Au Au

Further transformation

14

Cycloisomerization of 1,6-Enyne With Cycloisomerization of 1,6-Enyne With Skeletal RearrangementSkeletal Rearrangement

Echavarren, A.M. et al. Angew. Chem. Int. Ed. 2004, 14, 2402.

Echavarren, A.M. et al. Angew. Chem. Int. Ed. 2005, 44, 6146.

MeOOC

MeOOC

[AuCl(PPh3)]/AgSbF6 (2 mol%)

CH2Cl2, r.t., 25min91%

MeOOC

MeOOC

1 2

34

12

3

4

MeOOC

MeOOC

[AuCl(PPh3)]/AgSbF6 (2 mol%)


MeOOC

MeOOC

MeMe1 2

3

4

1 24

3

Single Cleavage

Double Cleavage

P Aut-Bu

t-Bu NCMe

SbF6

A

15

Mechanism – From Cyclobutene?Mechanism – From Cyclobutene?

Echavarren, A.M. et al. Chem. Eur. J. 2006, 12, 5916.

Z

H

AuH

Z

H

Conrotatory openingAu

MeOOC

MeOOC

COOMe

Pd catalyst,

60 oC COOMe

MeOOC

MeOOC

P Aut-Bu

t-Bu NCMe

SbF6

A

MeOOCMeOOC A (2 mol%)

CH2Cl2, r.t.(80%)

MeOOC

MeOOC

H

HH

25.7

21.6

16

Mechanism of Skeletal RearrangementMechanism of Skeletal Rearrangement

R2

AuR1

H

R2 R1

Au

HR2

R1

R2

R1

AuR1

H

R2

R2

H

AuR1

R1

R2

R2

R1

Single Cleavage

Double Cleavage

Echavarren, A.M. et al. Chem. Eur. J. 2006, 12, 5916.

17

Toste, F. D. et al. J. Am. Chem. Soc. 2007, 129, 5838.

Mechanism of Skeletal RearrangementMechanism of Skeletal Rearrangement

H

MeOOC

MeOOCPh

AuH

H

MeOOC

MeOOCPh

Au OSR2

O=SR2

H

MeOOC

MeOOCPh

OH

H

H

H AuMeOOCMeOOC

O=SR2

H

H

H OMeOOCMeOOC

Ph

HMeOOC

MeOOC

MeOOC

MeOOC N NR RL=

18

ContentsContents




Summary

19

Propargylic Ester Reactivity PatternPropargylic Ester Reactivity Pattern

Nolan, S. P. et al. Angew. Chem. Int. Ed. 2007, 46, 2750.

O O

R1

R2

R3Au

5-exo-dig

6-endo-dig

AuR3

OR2

O R1

R2 •

R3

OR1

OAuO O

R1

R2

Au

OO

R1

R2

AuR3

Carbene-typereactivity

alleneactivation

overall [3,3] rearrangement

R3

20

5-exo-dig VS 6-endo-dig5-exo-dig VS 6-endo-dig

Nolan, S. P. et al. Angew. Chem. Int. Ed. 2006, 45, 3647.


OAc

RAu

5-exo-dig OAc

RAuR = H

C-H insertionOAc

1,2-shift

•OAc

R

Au

ROac

[3,3]R = alkyl

1

2

R

Ph

O

Ph

O

t-Bu

18

•

Ph

O

Ph

O t-Bu18

Ph

Ph

O t-Bu

O18

6-endo-dig

21

Carbene Reactivity through 5-exo-digCarbene Reactivity through 5-exo-dig

Uemura, S. et al. Tetrahedron Lett. 2003, 44, 2019.


OAc

Ph

OAcPh

[RuCl2(CO)3]2

AuCl3 also work

OAc

Ar

OAcAr

2.5% [Au], 5% AgSbF6

MeNO2, 25 oC, 20min

[Au] =

O

O

O

O

PAr2AuCl

PAr2AuClAr =

t-Bu

OMe

t-Bu

76-94% e.e.

22

Allene Activation through 6-endo-digAllene Activation through 6-endo-dig

Zhang, L. et al. J. Am. Chem. Soc. 2005, 127, 16804.

Zhang, L. et al. J. Am. Chem. Soc. 2007, 129, 11358.

Pt>

Au

[3, 3] O

O

N

•

Bu

[M]

O

O

N Bu

M

N

O

O

Bu

[M]

M=Au

M=Pt

N

O

O

Bu

N

O

O

Bu

Bu

MeO

ON

N

O

O

Bu

Pt

23

ContentsContents




Summary

24

Vinyl Allene as SubstrateVinyl Allene as Substrate

Malacria, M. et al. J. Am. Chem. Soc. 2009, 131, 2993.

R1 R2R1 R2

•n-C5H11

m-CPBA

CH2Cl265%

On-C5H11

[O]

On-C5H11O

n-C5H11

Au

n-C5H11

Au

Aun-C5H11

•n-C5H11

Au n-C5H11

•n-C4H9

AuCl(PPh3) / AgSbF6 (2 mol%) n-C4H9


25

Vinyl Allene as SubstrateVinyl Allene as Substrate

Malacria, M. et al. J. Am. Chem. Soc. 2009, 131, 2993.

OAc

( )n

AuAcO

( )n( )n

AcO AcO HH

( )n

n = 1, 83%n = 2, 97% n = 3, 86% n = 4, 100%

n = 5, 99%

OAc

( )n•

OAc

( )n

Au

AcO

AcO Au AcO

Au

AcO

H

Au

AcO

H

AcO

Au

AcO

H

AcO

HH

[3,3]

26


Mascarenas, J. L. et al. J. Am. Chem. Soc. 2009, 131, 13020.

TsN

•

1

L*-AuCl, AgSbF6

CH2Cl2, -15 oCTsN

H

H

yield: 92%ee: 92%

O

OP N

Ph

PhL =

Allene for CycloadditionAllene for Cycloaddition

•MeOOC

MeOOCD

5%, LAuCl5%, AgSbF6

CH2Cl2, r.t.

MeOOC

MeOOCH

HDH

MeOOC

MeOOCH

D

H

1 2 3

L 2:3

P(OPh)3 100:0PPh3 67:33P(t-Bu)2(o-biPh) 4:96

H

27

ContentsContents




Summary

28

Early InvestigationEarly Investigation

Kochi, J. K. et al. J. Organomet. Chem. 1974, 64, 411.

Kochi, J. K. et al. J. Am. Chem. Soc. 1976, 98, 7599.

AuPh3P Me I Me

Au

Me

I

PPh3

Me

AuMe PPh3AuI PPh3

Au

Me

Me

PPh3

Me

Me Me

I Me AuMe PPh3 AuI PPh3Me Me

29

Gold Catalyzed Coupling ReactionGold Catalyzed Coupling Reaction

Corma, A. et al. Angew. Chem. Int. Ed. 2007, 46, 1536.

Guo, R. et al. J. Am. Chem. Soc. 2009, 131, 386.

I

AuCl(PPh3)

K3PO4

Cl (HO)2Bnano Au (0.05 mol%)

NaOH, H2O

Combine the Combine the ππ-acidity and Coupling -acidity and Coupling Reactivity Reactivity

Au

Au

NuNu

H

Nu

M (Pd)

M

Nu

R-M (B)Nu

Au

R

Nu

R

H


OH

•5mol% AuCl3 O

47%O

O

10%

Hashmi. A. S. K. et al. Eur. J. Org. Chem. 2006, 1387.

OH

•

AuIII

O

R

R

AuIII

O

R

R

AuIII

AuIII

R

R

AuIII

O

O

R

R

R

RO

O

R

R

R

R


Wegner. H. A. et al. Chem. Eur. J. 2008, 14, 11310.

O O HAuCl4 (5 mol%)

tBuOOH

O

O

O

O

yield: 13% - 67%

Zhang. L. et al. Angew. Chem. Int. Chem. 2009, 48, 3112.

NNFCl

2 BF4

Selectfluor

Oxidative CouplingOxidative Coupling

OAc

Me

Bu

[Ph3PAu]NTf2 (5 mol%)

SelectfluorBu

Bu

O

OMe

Me O

BuH

Me

19% 11%

O

BuAu

Me

O

BuF

Me

Oxidative CouplingOxidative Coupling


OAc

Me

Bu[LAuI]F

F

[LAuI]

OAc

BuAuI

Me

L

O

BuAuI

Me

L

H2O

H+, HOAc

NNFCl

2 BF4

NNCl

2 BF4

O

BuAuIII

Me

L

F

O

BuAuIII

Me

L

F

O

BuAuIII

Bu

O

MeMe

L F

BuBu

O

OMe

Me

R-M

O

BuAuIII

Me

L

F

R

L= Ph3P

O

BuR

Me

Reductive Elimination

• Au

OAcBu

Me

[3,3]


AuPPh3 AuPPh3 Ph

transmetallation

AuPPh3 Ph

F

Ph

AuPPh3 F

PhPh

F-

PhBF3K

PhB(OH)3

OAc

Me

Bu

BXnPhCH3CN, 80 oC

Selectfluor (2 equiv)

O

BuPh

Me

BuBu

O

OMe

Me O

BuH

Me

Catalyst PhBXn Solvent

1 2 3

1 2 3

[Ph3PAu]NTf2 PhBF3K MeCN PhPhonly

[Ph3PAu]NTf2 PhB(OH)2 MeCN/H2O 20:1 50% 17% 9%

Ph3PAuCl PhB(OH)2 MeCN/H2O 20:1 72% 9% 6%

[Ph3PAu]NTf2 PhB(OCH3)2 MeCN 30% 60% 0%

36

Gold and Palladium Combined for Gold and Palladium Combined for Cross-CouplingCross-Coupling

Hashmi, A. S. K. et al. Angew. Chem. Int. Ed. 2009, 48, 8283.

Blum, S. D. et al. Organometallics. 2009, 28, 1275.

•Me

i-PrO

OEt

Au(PPh3)Cl (1.0 eq.)

AgOTf (1.0 eq.)O

O

AuPh3P Me

i-Pr

PdCl2(dppf)] (1 mol%)

MeCNIPhO

O

PhMe

i-Pr

[L2PdCl2] [L2Pd0]

IPh

PdIIL2

Ph

I

OO

AuPh3P Me

i-Pr

O

Me

i-Pr

PdIIL2

PhO

Me

i-Pr

Ph[Ph3PAuI]

37

SummarySummary

π-acidity reactivity Complexity

1. substrate design

2. coupled with known reactivity (Nazarov, cycloaddition, carbocation)

3. tandem


Combine π-acidity reactivity and coupling reaction 1. Generate more complexity

2. from stoichiometric to catalytic

38

AcknowledgementAcknowledgement

Professor Weiping Tang

Tang Group

Practice talk attendees

Katherine Myhre

Jenny Werness Wei Zhang

Renhe Liu Dr. Suqing Zheng

Xiaoxun Li Dr. Min Zhang

Patrick Robichaux Na Liu

Kyle Dekorver Tianning Diao

39

Goddard, W. A.; Toste, F. D. et al. Org. Lett. 2009, 11, 4798.

Mascarenas, J. L. et al. J. Am. Chem. Soc. 2009, 131, 13020.

•MeOOC

MeOOC

AuR3P

MeOOC

MeOOC

AuR3P

MeOOC

MeOOC

AuR3P

Au

R3PAu

R3P

MeOOC

MeOOC

MeOOC

MeOOC

H

MeOOC

MeOOC

Relativistic Effect Relativistic Effect

• m=m0/[1-(v/c)2]1/2

• r decrease as m increase

• v increase, m increase, radius decrease, s and p orbital lower, d higher

• Unusual higher electronegativity, ionization energy, lower 6s and 6p (LUMO), higher 5d, strong Au-L bond

Pyykko, P. et al. Acc. Chem. Res. 1979, 12, 276.

General Reactivities of Gold CatalysisGeneral Reactivities of Gold Catalysis

[Au]Nu π-Acidity:

Traditional organometallic reactivity:

Oxidative addition and reductive elimination

Transmetallation

C-H activation:

Hydrogenation and Oxidation

H

H

AuIII Au

Au

EE

E

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