Michael reactions of pseudoephedrine amide enolates: Effect of LiCl on syn/anti selectivity

被引：33

作者：

Smitrovich, JH ^{[1
]}

DiMichele, L ^{[1
]}

Qu, CX ^{[1
]}

Boice, GN ^{[1
]}

Nelson, TD ^{[1
]}

Huffman, MA ^{[1
]}

Murry, J ^{[1
]}

机构：

[1] Merck & Co Inc, Merck Res Labs, Dept Proc Res, Rahway, NJ 07065 USA

来源：

JOURNAL OF ORGANIC CHEMISTRY | 2004年 / 69卷 / 06期

关键词：

D O I：

10.1021/jo035564a

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

The stereochemical outcome of the asymmetric Michael reaction of pseudoephedrine amide enolates changes dramatically in the presence of LiCl. Reaction of the enolate in the absence of LiCl results in formation of the anti Michael adduct with high selectivity, whereas in the presence of lithium chloride the syn adduct is favored. This method provides access to enantiomerically enriched trans-3,4-disubstituted delta-lactones from the anti Michael adducts by a two step reduction/lactonization sequence. Information obtained from NMR studies indicates that, under both enolization conditions, the (Z)-enolate is formed. A model to explain the turnover in selectivity based on NMR evidence is presented.

引用

页码：1903 / 1908

页数：6

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