PHASE-TRANSFER CATALYSIS .51. CATALYST EFFECTS ON REACTIONS OF ALPHA-BETA-UNSATURATED KETONES AND ESTERS WITH HALOFORMS UNDER PHASE-TRANSFER CATALYSIS

被引：28

作者：

DEHMLOW, EV

WILKENLOH, J

机构：

[1] Fakultät für Chemie, Universität Bielefeld, Bielefeld, D-4800

来源：

CHEMISCHE BERICHTE | 1990年 / 123卷 / 03期

关键词：

Dihalocarbenes / Trihalomethane anions / Michael addition vs. carbene process / Phase‐transfer catalyst; influence of structure;

D O I：

10.1002/cber.19901230325

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Catalyst Effects on Reactions of α, β‐Unsaturated Ketones and Esters with Haloforms under Phase‐Transfer Catalysis Reactions of acceptor‐substituted alkenes with haloform/sodium hydroxide and PT‐catalyst result in dihalocarbene additions competitive to Michael additions, with or without consecutive cyclization, and further reactions. Product compositions are strongly dependent on the nature of the phasetransfer catalyst: Sterically unhindered quaternary ammonium ions and benzo‐crown ethers favour processes via carbenes, large delocalized (soft) cations foster primary Michael additions. Thus, tert‐butyl cis‐crotonate is dichlorocyclopropanated stereospecifically with NMe4Cl. The respective stereospecific CBr2 conversion is successful only with PhHgCBr3. Copyright © 1990 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim

引用

页码：583 / 587

页数：5

共 9 条

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