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Radical Rearrangement: A Strategy for Conversion of Cephalosporin to 1-Carba(dethia)cephalosporin

✍ Scribed by Noreen G. Halligan; Raymond F. Brown; Douglas O. Spry; Larry C. Blaszczak

Publisher: Elsevier Science
Year: 2000
Tongue: French
Weight: 139 KB
Volume: 56
Category: Article
ISSN: 0040-4020
DOI: 10.1016/s0040-4020(00)00417-8

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✦ Synopsis

AbstractÐA radical rearrangement approach to semisynthesis of the carbacephem class of b-lactam antibiotics is reported. The crucial bond construction in assembly of the carbacephem framework was accomplished by intramolecular C±C bond formation between an azetidin-2-one-4-yl and a pendant diene ester. This reactive intermediate was generated by fragmentation of a cephem derived radical followed by loss of sulfur dioxide. The radical precursor was prepared in 63% yield over four steps and the subsequent rearrangement reaction provided carbacephem products in a single step at 23% yield.

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