Radical cyclisations of methylenecyclopropyl azetidinones-synthesis of novel tricyclic β-lactams

被引：28

作者：

Penfold, DJ

Pike, K

Genge, A

Anson, M

Kitteringham, J

Kilburn, JD ^{[1
]}

机构：

[1] Univ Southampton, Dept Chem, Southampton SO17 1BJ, Hants, England

[2] Glaxo Wellcome Res Ltd, Stevenage SG1 2NY, Herts, England

[3] SmithKline Beecham Pharmaceut, Dept Synthet Chem, Harlow CM19 5AW, Essex, England

来源：

TETRAHEDRON LETTERS | 2000年 / 41卷 / 52期

基金：

英国工程与自然科学研究理事会;

关键词：

methylenecyclopropane; cuprate; radical cyclisation; beta-lactam;

D O I：

10.1016/S0040-4039(00)01860-8

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

Addition of lithium bis(methylenecyclopropyl)cuprates to acetoxy azetidinones gives methylenecyclopropyl azetidinones, which can be converted to various radical cyclisation precursors. Attempted 4-exo cyclisation of 3 led only to reduced product, while cyclisation of 5, using CuCl/bipy, gave a carbacephem, via a 5-exo cyclisation, but in low yield. Cyclisation of 6 and 7, however, gave novel tricyclic beta -lactams, as the result of 7-endo cyclisation, in good yield, and a cyclisation of bromide 23 led to the tricyclic beta -lactam 24, via a radical cascade sequence. (C) 2000 Elsevier Science Ltd. All rights reserved.

引用

页码：10347 / 10351

页数：5

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