EFFECTS OF LITHIUM-SALTS ON THE STEREOCHEMISTRY OF KETONE ENOLIZATION BY LITHIUM 2,2,6,6-TETRAMETHYLPIPERIDIDE (LITMP) - A CONVENIENT METHOD FOR HIGHLY E-SELECTIVE ENOLATE FORMATION

被引：152

作者：

HALL, PL ^{[1
]}

GILCHRIST, JH ^{[1
]}

COLLUM, DB ^{[1
]}

机构：

[1] CORNELL UNIV,DEPT CHEM,BAKER LAB,ITHACA,NY 14853

来源：

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | 1991年 / 113卷 / 25期

关键词：

D O I：

10.1021/ja00025a023

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Studies of the reactivity of lithium 2,2,6,6-tetramethylpiperidide (LiTMP) with added lithium salts are described. The E/Z selectivity of 3-pentanone enolization by LiTMP displays a marked decrease as a function of added ketone (percent conversion). The enolization also shows a notable maximum of 50:1 selectivity at 0.3-0.4 equiv of added LiCl and an approximate asymptotic approach to 50-60:1 selectivity when > 1.0 equiv of LiBr are added. The LiTMP-LiBr complex generated from 2,2,6,6-tetramethylpiperidinium bromide affords enolates with generally high regio- and stereoselectivity as shown by several representative enolizations. The selectivities appear to have exclusively kinetic origins and are suggested to stem from the intervention of LiTMP-LiX mixed aggregates characterized in the following paper.

引用

页码：9571 / 9574

页数：4

共 60 条

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