A Novel Synthesis of the Monobactam Antibiotic Carumonam

Article abstract of DOI:10.1021/jo00258a020

A novel synthesis of the monobactam 4, a precursor of the antibiotic carumonam (3), has been achieved via the epoxide methyl (2R,3S)-4-acetoxy-2,3-epoxybutyrate (10).The latter was prepared from calcium L-threonate in three steps and 85percent overall yield.In a related study, ethyl (2R,3S)-4-hydroxy-2,3-epoxybutyrate (17) was prepared from L-(+)-tartaric acid <(2R,3R)-tartaric acid> in 45percent overall yield.Treatment of the sodium salt derived from 10 or 17 with ammonia led to a stereo- and regiospecific opening of the oxirane ring to give 20, after esterification, amide formation, and protection of the amino group.Conversion of 20 into 4 was accomplished by selective protection of the primary hydroxy group with chloroacetyl chloride, mesylation, sulfonation with 2-picoline-SO3, and ring closure with potassium bicarbonate.