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

✍ Scribed by David J Penfold; Kurt Pike; Anthony Genge; Mike Anson; John Kitteringham; Jeremy D Kilburn

Publisher
Elsevier Science
Year
2000
Tongue
French
Weight
105 KB
Volume
41
Category
Article
ISSN
0040-4039

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✦ Synopsis

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 b-lactams, as the result of 7-endo cyclisation, in good yield, and a cyclisation of bromide 23 led to the tricyclic b-lactam 24, via a radical cascade sequence.

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ChemInform Abstract: Radical Cyclizations of Methylenecyclopropyl Azetidinones — Synthesis of Novel Tricyclic β-Lactams.
✍ David J. Penfold; Kurt Pike; Anthony Genge; Mike Anson; John Kitteringham; Jerem 📂 Article 📅 2001 🏛 John Wiley and Sons ⚖ 40 KB 👁 1 views

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