Unexpected ambidoselectivity in crossed-aldol reactions of α-oxy aldehyde trichlorosilyl enolates

被引：11

作者：

Denmark, Scott E. ^{[1
]}

Ghosh, Sunil K. ^{[1
]}

机构：

[1] Univ Illinois, Dept Chem, Roger Adams Lab, Urbana, IL 61801 USA

来源：

TETRAHEDRON | 2007年 / 63卷 / 35期

基金：

美国国家科学基金会;

关键词：

aldol enolate; deuterium labeling; enantioselective; diastereoselective;

D O I：

10.1016/j.tet.2007.04.009

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

The ambido-, stereo- and enantioselectivity of the phosphoramide-promoted aldol reactions of alpha-oxy aldehyde trichlorosilyl enolates with benzaldehyde has been investigated. Analysis of the products from alpha-tert-butyldimethylsilyloxy alpha-deuterioacetaldehyde trichlorosilyl enolate confirmed that this 1,2-bis-silyloxyethene derivative reacted as a tert-butyldimethylsilyl enolate rather than trichlorosilyl enolate in the aldol reaction with very high ambidoselectivity. The phosphoramide-coordinated trichlorosilyl group acted as an organizing center for the aldol reaction. From the aldol process, excellent anti-diastereoselectivity could be achieved. The enantioselectivity remained moderate to low for both anti- and syn-diastereomer with a wide range of phosphoramide catalysts. alpha-Triisopropylsilyloxy, phenoxy and benzyloxy acetaldehyde trichlorosilyl enolates also reacted in a similar fashion with benzaldehyde to give aldol products with varying degrees of selectivities. (c) 2007 Elsevier Ltd. All rights reserved.

引用

页码：8636 / 8644

页数：9

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