Asymmetric Synthesis and Structure‐Activity Relationship of the Four Stereoisomers of the Antibiotic Amidinomycin Part 1: The Synthesis

The natural amidinomycin (( 1 R , 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 produce methyl cis‐N ‐(1‐phenylethyl)‐3‐aminocyclo‐pentanecarboxylates ( 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 .