A Synthesis of (3S,4R)-3-[(R)-1-(t-Butyldimethylsilyloxy)ethyl]-4-carboxymethyl-2-azetidinone, the Thienamycin Intermediate, from (S)-Ethyl Lactate
The title thienamycin intermediate was efficiently synthesized from (S)-ethyl lactate (3) by subjecting (3S,4S)-3-acetyl-4-[(S)-1-benzyloxyethyl]-2-azet idi none readily obtainable from 3, to sequential reactions in which base catalyzed elimination and regioselective hydroboration were employed as the key processes.