Catalytic, Asymmetric Synthesis of the Carbacephem Framework

Article abstract of DOI:10.1021/jo00096a031

A catalytic, asymmetric synthesis of the carbacephem β-lactam framework is reported.The initial asymmetric center was established by catalytic hydrogenation of β-keto ester 12 with (S)-Ru-BINAP.The β-lactam ring was prepared using the hydroxamate approach (14 -> 15).The nitrogen substituent at C7 was introduced by the nucleophile transfer reaction (15 -> 17), and the six-membered ring of the carbacephem was prepared by a directed Dieckmann condensation (24 -> 25).