4582

cop-l

R R

1 syn-2

Table 1. C2,33Wittig Rearrangement of Alkenyloxyacetic Acid Esters (lIa)

Starting ester (1) Product (21 Entry Additive c)

R Confn. at Yieldb) Oiastereom. Confn. of syn-isomer % ee

2'-Double l'-Carbon (91 4-Double 3-Carbon of syn-

bond atom

ratiod) - e) _

syn : anti bond atom isomer --

1 H non 20 2 :l

2 H !L, Cp2ZrC12 15 7 :l

3 H (I, non 14 4.5 : 1

4 H (F, Cp2ZrC12 47 45 : 1 5 Me !L, non 72 4:l _f)

6 Me (E) (2, Cp2ZrC12 91 100 : 1 (21 >96

7 n-Bu (L, (R) Cp2ZrC12 81 61 :l (El >96

8 n-Ott (L, (R) Cp2ZrC12 70 90 : 1 (R) >96

9 i-Pr (El (R) Cp2ZrC12 26 50 : 1 @g) (R) '96

a) Reaction conditions; see the text and reference 5. b) Isolated yield. cl Determined

by 'H NMR (90 MHz) under the presence of a chiral shift reagent, Eu(hfcj3. d) Determined by

'H NMR. e) For the determination of configuration, the product was converted into the corresponding a-methylcarboxylic acid by successive catalytic hydrogenation, LAH reduction, and Ru04 oxidation, and the sign of optical rotation was compared with the authentic datum. fl A

mixture of E/Z= ca. 6/4. g) Determined by 'H NMR. No (El-isomer was detected. -

This work was supported in part by a Grant-in-Aid for Scientific Research (No. 59470020)

from the Ministry of Education, Science, and Culture, Japan. The authors also thank Professor

T. Nakai of the Department of Chemical Technology, Tokyo Institute of Technology, for his

valuable informations and discussion on this subject.

References and Notes

1) M.Uchikawa, T.Hanamoto, T.Katsuki, and M.Yamaguchi, preceding communication on this issue.

2) C2,33Wittig rearrangement of Li enolates derived from P'-alkenyloxyacetic acid has been

reported to give a moderate stereoselectivity; T.Nakai, K.Mikami, S.Taya, Y.Kimura, and T.

Mimura, Tetrahedron Lett., 22, 69 (1981). 3) Optically active secondary alcohols obtained

by asymmetric epoxidation CT.Katsuki and K.B.Sharpless, J. Am. Chem. Sot., 102, 5974 (1980);

V.S.Martin, S.S.Woodard, T.Katsuki, Y.Yamada, M.Ikeda, and K.B.Sharpless, ibid, 103, 6237

(198113 were converted into 2'-alkenyloxyacetic acids by Nakai's procedure (reference 2).

4) One (Zl-selective example has been reported with a substrate having a trisubstituted

double bond; W.C.Still and A.Mitra, 3. Am. Chem. Sot., 100, 1927 (1978). 51 At -78 "C, Li

enolates rearrange to some extent resulting in the decrease of diastereoselectivity.

(Received in Japan 27 May 1986)