Asymmetric synthesis and structure-activity relationship of the four stereoisomers of the antibiotic amidinomycin .1. The synthesis

The natural amidinomycin ((1R, 3S)-14) and its three stereoisomers are synthesized from homochiral 3-oxocyclopentanecarboxylic acids (1a) by asymmetric methods, which are based on an asymmetric reductive amination to produced methyl cis-N-(1-phenylethyl)-3-aminocyclopentanecarboxylates (3b) via optically active methyl N-(1-phenylethyl)-3-iminocyclopentane-carboxylates (2b) for the cis-isomers of 14. Optically pure trans-3-aminocyclopentane-carboxylic acids (4a) are obtained from the homochiral keto acids 1a via asymmetric reductive amination of 3-hydroxy-iminocyclopentanecarboxylic acids (5a) and lead to the trans-isomers of 14.