SYNTHETIC STUDIES ON THE KEY COMPONENT OF THE NEW-GENERATION OF QUINOLONECARBOXYLIC ACID, DU-6859 .1. SYNTHESIS OF (1R,2S)-2-FLUOROCYCLOPROPYLAMINE BY THE USE OF OPTICAL RESOLUTION

The title synthesis was achieved by employing highly cis-selective cyclopropanation of N-benzyl-N-vinylcarbamates with zinc-monofluorocarbenoid, deprotection of the formed N-benzyl-N-(cis-2-fluorocyclopropyl)carbamates, and optical resolution of the resulting dl-cis-2-fluorocyclopropylamine by the use of l-menthyl chloroformate as a resolving agent. The cis-selectivity observed for the key cyclopropanation could be explained by the bent transition state model.