STEREOSELECTIVE PROTONATION OF CARBANIONS .4. ENANTIOSELECTIVE PROTONATION OF LACTONE ENOLATES

被引：22

作者：

GERLACH, U ^{[1
]}

HAUBENREICH, T ^{[1
]}

HUNIG, S ^{[1
]}

机构：

[1] UNIV WURZBURG,INST ORGAN CHEM,HUBLAND,D-97074 WURZBURG,GERMANY

来源：

CHEMISCHE BERICHTE | 1994年 / 127卷 / 10期

关键词：

PROTONATION; ENANTIOSELECTIVITY; LACTONE ENOLATES; CHIRAL PROTON SOURCES;

D O I：

10.1002/cber.19941271021

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

The prochiral lithium enolates derived from the five-membered lactones rac-1 and rac-2 were protonated by 37 OH-and 21 NH-chiral proton sources in THF at -78-degrees-C. The enantioselectivities, determined directly from the reaction mixture by chiral HPLC, are always higher for system 1, probably due to restricted rotation of the phenyl group in 1Li at low temperature (NMR) and range from 0-54% ee. The strongest stereodifferentiation is observed if the OH or NH acids carry an adjacent O- or N-containing group (structures G-J) which allows complexation with the lithium ion. A plausible transition state involving the dimeric lithium enolate is proposed.

引用

页码：1969 / 1980

页数：12

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