The synthesis of GYKI-14766 is as follows: N2-tert-Butoxycarbonyl-L-arginine (I) was converted to the N6-benzyloxycarbonyl derivative (II). Treatment of (II) with isobutoxycarbonyl chloride and N-methylmorpholine gave the aminolactam (III). Dicyclohexylcarbodiimide-mediated esterification of N-benzyloxycarbonyl-D-phenylalanine (IV) with 2,4,5-trichlorophenol gave the active ester (V), which was coupled with L-proline to the dipeptide (VI). Methylation with iodomethane afforded the N-methyl derivative isolated as the cyclohexylamine salt (VII). The fragments (III) and (VII) were coupled via the mixed anhydride of (VII), generated as in the case of (II), giving the tripeptide lactam (VIII). Reduction with lithium aluminum hydride at low temperature converted (VIII) to the aldehyde (IX), which was finally deprotected to the end product.

The synthesis of GYKI-14766 is as follows: N2-tert-Butoxycarbonyl-L-arginine (I) was converted to the N6-benzyloxycarbonyl derivative (II). Treatment of (II) with isobutoxycarbonyl chloride and N-methylmorpholine gave the aminolactam (III). Dicyclohexylcarbodiimide-mediated esterification of N-benzyloxycarbonyl-D-phenylalanine (IV) with 2,4,5-trichlorophenol gave the active ester (V), which was coupled with L-proline to the dipeptide (VI). Methylation with iodomethane afforded the N-methyl derivative isolated as the cyclohexylamine salt (VII). The fragments (III) and (VII) were coupled via the mixed anhydride of (VII), generated as in the case of (II), giving the tripeptide lactam (VIII). Reduction with lithium aluminum hydride at low temperature converted (VIII) to the aldehyde (IX), which was finally deprotected to the end product.