Abstract
An imidazolide (4) obtained from carbobenzoxy-NG=-nitro-L-arginine (3) was reduced with lithium aluminum hydride to give carbobenzoxy-NG=-nitro- L-argininal (5) in good yield. The aldehyde (5) was converted into NG=-nitro-Largininal semicarbazone (7) which was coupled with an active ester of various acylated leucines or isoleucines and then deblocked, giving leupeptins and their analogs, as listed in Table 1. Antiplasmin activities of these compounds are discussed.
