合成路线1

In an alternative method, N,N'-bis-(benzyloxycarbonyl)-(R)-ornithine (I) is treated with PCl5 to afford the corresponding acid chloride, which is then converted to diazo ketone (II) with ethereal diazomethane. Rearrangement of (II) under Arndt-Eistert conditions in the presence of silver benzoate leads to the beta-lysine derivative (III). After saponification of the methyl ester (III), the resultant carboxylic acid (IV) is coupled to ethyl 1-methylhydrazinoacetate (V) via the mixed anhydride with isobutyl chloroformate, to give hydrazide (VI). Alkaline hydrolysis of the ethyl ester (VI) yields acid (VII). The N-carbobenzoxy groups are finally removed by hydrogenolysis to furnish the title compound.