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Paper | Regular issue | Vol 34, No. 1, 1992, pp.67-83
Published online, 1st January, 1970
DOI: 10.3987/COM-91-5882
Anionic 4+2 Cyclization Route to 3-Sulfur Substituted Isocephem Analogs

Sagar Shakya and Tony Durst*

*Ottawa-Carleton Chemistry Institute, Department of Chemistry, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada

Abstract

Four different isocephem analogs have been synthesized. The key step in the construction of the bicyclic ring involves an anionic 4+2 cyclization. The lithio derivative obtained from a suitably protected N-carboxymethyl-2-azetidinone was condensed with carbon disulfide. Subsequent intramolecular alkylation of the 4-tosyloxymethyl substituent by the resultant sulfur nucleophile completed the cyclization sequence.