合成路线1

-(Benzyloxycarbonyl)-L-leucine (I) was activated as the mixed anhydride with isobutyl chloroformate and then coupled with N,O-dimethylhydroxylamine to produce the N-methoxyamide (II). Reduction of (II) with LiAlH4 at -78 C furnished aldehyde (III), which was converted to the corresponding diethyl acetal (IV) upon treatment with triethyl orthoformate. Subsequent hydrogenolytic removal of the benzyloxycarbonyl group of (IV) afforded leucinal diethylacetal (V). Coupling of N-Fmoc-nitroarginine (VI) with aminoacetal (V) via activation as the mixed anhydride with isobutyl chloroformate provided the protected dipeptide aldehyde (VII). The Fmoc protecting group of (VII) was then cleaved by using diethylamine in DMF-EtOAc to provide the intermediate (VIII).