NOTES 275

with :a sirnil-ir expression for h', escept that e,, 02 are trans- posed. When these are squared, combined, and the poten- tial function differentiated, the following components :ippear in the potential energy matrix

V.Y~.X~ = VX,.X, = V X ~ ~ X ~ = VX~,X> = 2k.t R R2a R? vo,,ol = voJBI,02 = A [ ( 1 - 2 sin p) + sin"] +

vo,.o, = vo2,0, = -2.4 [ ( 1 - 2 R sin p) 2 sin A] + -

2kbip(6) Ro2 COS2P

where we have set

The secular determinant is therefore 2kat - X w 2 2kst 0 0

2kat ?kst - M w 2 0 0 0 0 Vml - Izw2 Ve,c 0 0 Vho, V w 2 - I d

for which the roots are

w = o w 1 = 2 d / K , t l M

w9. = 2/( V@,@, + V@,&)/IZ w3 = v'( Vole1 - Vola) / Iz These correspond to the frequencies listed in Table VI.

The Out-of-plane Vibrations.-The distances dH and d H l of Fig. 2a appear again in Fig. 2b, being the distances (in the inclined planes) from the axes y(1) and y(2) to the points 1 and 2, respectively. The latter are determined by the intersection of the inclined planes with the normal to the

original plane, which passes through the hydrogen atom. As before

kb,,~a)/kb,,($) A R Z / R I and a / w Rl/RZ

2Vb(op) = kbop(a) [a2 + 2 $ 2 1 + similar terms in a',~'

The distance - 12 = d& - d ~ & + G(O6 - Os)

= Ria + R?$ Hence

Let

Then, the components of the potential energy matrix are Vsb = v66 = B(dH2 f dH")

vf,6 vcs = - 2 B d ~ d ~ ' v - v - v - 'V86 = - v58 = - VSS = - v67 = - v 7 S 57 - 76 - 68 -

= BG(dH - d")

The secular determinant takes the form Vi7 = V88 = - V78 = - Vs7 = 2 B G 2

vsj - I,w2 v6 6 V67 - v67 v5 6 vjs - IyW' - V67 V67

V67 - V67 v77 - I& - v77 v7, - IxwZ - v67 767 - v77

the roots of which may be expressed as

W = 0 W4 = d( v65 f V66)/1y

and

2v77 - I*o' 2v67 I = O 1 (V65 -2;; - IYw2

JTHACA, iY. Y.

NOTES

Ethyl CV- ( a'-Ethoxy-p'-phenylethylideneamin0)- P,P-diethoxypropionate

BY HOMER ADKINS~ AND GERALD GILBERT^ RECEIVED JULY 31, 1953

The projected synthesis of a series of substituted oxazolines required ethyl a-(a'-ethoxy-/?'-phenyl- ethy1ideneamino)-P,P-diethoxypropionate (I) or the corresponding aldehyde as an intermediate. How- ever, other investigations indicate that the pres- ence of the free aldehyde is attended by cyclization. Thus, the condensation of ethyl phenyliminoacetate with the sodium enolate of ethyl N-formyl-a- formylglycinate in the presence of hydrogen chlo- ride has been shown to yield 2-benzyl-4-carbethoxy- oxazole.3 The substituted iminoester, I1

(1) Deceased August 10, 1949. (2) Rohm and Haas Co., Phila., Pa. (3) H. Adkins, R. M Boss and D. C. Sshroeder, THIS JOURNAL, 78,

6401 (1860).

KOCH=CCOOEt I I N II

CeHsCHz&OEt I1

which is stabilized by the potassium enolate, was prepared by Tiffany4 by another route. However, several attempts to produce I from this substance in the presence of some acetal-forming reagents again yielded 2-benzyl-4-carbethoxyoxazole.

The present investigation indicates that cycliza- tion can be avoided by preparing the acetal prior to the iminoester condensation. The reaction of ethyl P,P-diethoxyalanate with ethyl phenylimino- acetate hydrochloride proceeded readily in ethylene dichloride a t room temperature and I was isolated in 70% yield.

(4) B. D. Tiffany, Ph.D. Thesis, University of Wisconsin, 1949; cf. J. W. Cornforth, E. Fawaz, L. J. Goldrworthy and R. Robinson. J . Ch8m. S@G,fi 1649 (1849).

2 76 NOTES

NH .H C 1

(EtO)&HCHIVH-XOOEt + C6H5CH2C0Et

nitrogen attached to what had carbon atom of the chalcone.

S I

I CbHSCH2COEt

I

In some runs, phenylacetamide, which can arise from the decomposition of ethyl phenyliminoace- tate hydr~chloride,~ was also found in the distillate.

Experimental Ethyl ~-(~'-Ethoxy-P'-phenylethylideneamino)-P,p-di-

ethoxypropionate (I).-In a 500-ml. flask fitted with a Hershberg stirrer were placed 25 g. (0.122 mole) of ethyl (3,P-diethoxyalanate6 and 37 g. (0.175 mole) of ethyl phenyl- iminoacetate hydrochloride' in 200 ml. of ethylene dichlo- ride. The mixture usually became warm a t the start and was cooled in an ice-bath. The bath was then removed and stirring continued at room temperature for 24 hours. The ammonium chloride was filtered from the product, the solvent removed under reduced pressure, and the residue fractionated through a 12-cm. Vigreux column; b.p. 125- 127" (0.04 mrn.), yield 30 g. (70%). The product was a light yellow oil, soluble in ether and insoluble in 10% hydro- chloric acid.

Anal. Calcd. for C19H2905N: N, 3.99; C$HaO, 51.28. Found: S (Kjeldahl), 4.01, 3.96, 3.95; C2H60 (Zeisel), 51.12, 50.80.

In some runs, small amounts of a white crystalline solid, m p. 160-161", codistilled with the product. A mixed melting point with an authentic sample of phenylacetamide shoiTed no depression.

Anal. Calcd. for CgHJYO: C, 71.09; H, 6.71; N, 10.36. Found: C, 70.80; H, 6.69; hT, 10.41.

( 5 ) S. hl. McElvain and B. E. Tate, THIS JOURNAL, 73, 2233 (1951). (6) "The Chemistry of Penicillin," Princeton University Press,

(7) S. hl. hIcElvain and C. I,. Stevens, THIS JOURNAL, 68, 1917 Princeton, h-. J . , 1949, p. 512.

(1946).

THE LABORATORY OF ORGANIC CHEMISTRY UNIVERSITY OF WISCONSIN M a D I S O N , \\'ISCONSIS

Spectroscopic Evidence for the Structure of Isoxazo- lines and the Mechanism of their BY R. PERCY BARSES, GLADYS ESTELLE PINKNEY3 AND

GEORGE MCK. PHILLIPS4

RECEIVED JULY 31, 1953

In 1931 Blatt5 showed that isoxazolines gave no methane on treatment with methylmagnesium iodide and on this basis assigned structure I to them. The same year Blatt and Stone6 showed that isox- azolines derived from substituted chalcones had

(1) This work was supported by a grant from the Research Cor- poration of New York for the purchase of a Perkin-Elmer 12C infrared spectrometer.

(2) The authors wish to acknowledge the invaluable aid of Mr. Jonas Carroll of the Food and Drug Administration, U. S. Department of Health, Education and Welfare, and the use of their Perkin-Elmer 21 infrared spectrometer.

(3) Research Amociatc in Chemistry, Howard University, Washing- ton, D. C.

(4) In partial f?i!€il!ment of the requirements for the mantar'a degree In chemibtfy.

( f i ) A. H. Btatt) %it9 J O ~ J R X A ~ . , 68, 1133 (1931). [fi) A , R, Q l ~ t t pHd j t?, ntnn5. i h j d . , 88, 4 1 R O ~ l W * > .

1701. 76

been the carbonyl

(7

C_)-C=CH-C--\ '2 0- S

I '

c1) -C=CH-C-

SH-----hT I11

ll 0, We have now examined the infrared spectra of a

number of isoxoazolines, their related isoxazoles, and a pyrazole in the belief that additional informa- tion as to the structure of isoxazolines would thereby be obtained.

X,.j-Diphenyl-, 3-p-bromophenyl-3-phenyl-, X - phenyl-3-p-bromophenylisoxazolines and their cor- responding isoxazoles all showed strong absorption a t 5 . 8 , ~ ~ attributable to the -C=N- grouping, but no absorption in the 2-9p region. In contrast, 3,5-diphenylpyrazole shows absorption a t 2 . 9 ~ owing to the presence of an -NH- grouping. These findings confirm the assignment of structure I to the isoxazolines, and Barnes and Dodson were in error in assigning to 3-p-bromophenyl-<?-phenyl- isoxazoline and the corresponding isoxazole the R- phenyl-5-p-bromophenyl structure.'

In recent studies by Barnes and co-worker8 it was found that chalcones with highly hindered carbonyls such as benzalacetomesitylene do not form isoxazolines but yield substituted hydroxyl- amines instead. They isolated the substituted hydroxylamine hydrochloride which upon rear- rangement and hydrolysisg yielded benzylmesityl- glyoxal, as Blatt's corresponding methoxy deriva- tives rearrange and hydrolyze to alpha diketones.

From the isomeric benzal-p-bromoacetophenone and p-bromobenzalacetophenone we prepared the isomeric hydroxylamino ketones IV and V, re- spectively, isolating them as their hydrochlorides.

-CH-CH2-C& C I > - - B r

NHOH 11'

= I

B r ~ - C H - C H - C O ~ 1 SHOH

The hydrochlorides of the hydroxylamino ke- tones IV and V were subjected to treatment with hydroxylamine hydrochloride and excess potassium hydroxide, and they yielded isoxazolines VI and VII, respectively.

a - C H - C H , - C - - < I Z ) - B r I ,I 0 s

VI (7) R. P. Barnes and L. &I Dodson, ;bid., 6'7. 182 (1945). (8) Nancita Robinson, unpublished master's thesis, Departmen* of

Chemistry, Howard University, 1949. (8 ) A H, Ria% THw Jounlr*c, PI, a404 (ipa9).