An asymmetric Kharasch reaction mediated by D-xylose: long range diastereocontrol

被引：12

作者：

Enholm, EJ ^{[1
]}

Bhardawaj, A ^{[1
]}

机构：

[1] Univ Florida, Dept Chem, Gainesville, FL 32611 USA

来源：

TETRAHEDRON LETTERS | 2003年 / 44卷 / 19期

基金：

美国国家科学基金会;

关键词：

free radical; diastereoselective; atom transfer; Kharasch reaction;

D O I：

10.1016/S0040-4039(03)00756-1

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

An asymmetric Kharasch-type atom transfer reaction was studied under 13 different sets of reaction conditions in order to obtain the highest levels of diastereoselection. The highest ratio of 12.5:1 (71%) was observed at low temperatures (-78degreesC) using the Lewis acid Eu(OTf)(3). Because the new asymmetric center is so distant from the D-xylose, we propose a transition state involving two sugars. The conversion of the major product to a naturally occurring chiral gamma-butyrolactone, under basic conditions, is described which also confirmed the diastereoselectivity and absolute stereochemistry of the Kharasch reaction. (C) 2003 Elsevier Science Ltd. All rights reserved.

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页码：3763 / 3765

页数：3

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