N2-tert-Butoxycarbonyl-N6-benzyloxycarbonyl-L-arginine (I) is converted by treatment with isobutyl oxycarbonyl chloride (A) and N-methylmorpholine (B) to the lactam (II), and the tert-butoxycarbonyl group is cleaved off to give the aminolactam (III), which is coupled with N-tert-butoxycarbonyl-D-phenylalanyl-L-proline (IV) to the tripeptide (V) using the mixed anhydride method as in the first step. The lactam carbonyl is reduced with LiAlH4 to an aldehyde group present as the cyclic a aminoalcohol (VI). Removal of the benzyloxycarbonyl blocking group provides GYKI-14451. In solution the aldehyde group is either in the cyclic alpha-aminoalcohol form or is hydrated.

N2-tert-Butoxycarbonyl-N6-benzyloxycarbonyl-L-arginine (I) is converted by treatment with isobutyl oxycarbonyl chloride (A) and N-methylmorpholine (B) to the lactam (II), and the tert-butoxycarbonyl group is cleaved off to give the aminolactam (III), which is coupled with N-tert-butoxycarbonyl-D-phenylalanyl-L-proline (IV) to the tripeptide (V) using the mixed anhydride method as in the first step. The lactam carbonyl is reduced with LiAlH4 to an aldehyde group present as the cyclic a aminoalcohol (VI). Removal of the benzyloxycarbonyl blocking group provides GYKI-14451. In solution the aldehyde group is either in the cyclic alpha-aminoalcohol form or is hydrated.

N2-tert-Butoxycarbonyl-N6-benzyloxycarbonyl-L-arginine (I) is converted by treatment with isobutyl oxycarbonyl chloride (A) and N-methylmorpholine (B) to the lactam (II), and the tert-butoxycarbonyl group is cleaved off to give the aminolactam (III), which is coupled with N-tert-butoxycarbonyl-D-phenylalanyl-L-proline (IV) to the tripeptide (V) using the mixed anhydride method as in the first step. The lactam carbonyl is reduced with LiAlH4 to an aldehyde group present as the cyclic a aminoalcohol (VI). Removal of the benzyloxycarbonyl blocking group provides GYKI-14451. In solution the aldehyde group is either in the cyclic alpha-aminoalcohol form or is hydrated.