A Novel Ring-Closure Strategy for the Carbapenems: The Total Synthesis of (+)-Thienamycin

Article abstract of DOI:10.1021/jo00297a026

Intramolecular Michael cyclization of an N-<(alkoxycarbonyl)methyl>-4-(3-nitro-2-propenyl)-3-oxoazetidin-2-one available in optically pure form leads to the corresponding carbapenam skeleton.Further elaboration via oxidative cleavage of an exocyclic nitromethylene group gives an advanced intermediate, which was transformed into (+)-thienamycin.The stereochemistry of the Michael cyclization and the pitfalls of protective group chemistry are discussed.