合成路线1

The protection of the NH group of siastatin B (I) with tert-butoxycarbonyl anhydride gives the N-protected intermediate (II), which is treated with benzaldehyde diethyl acetal and trimethylchlorosilane yielding the benzylidene ketal (III). The esterification of (III) with chloromethyl(2-methoxyethyl)ether and DIEA in DMF affords the activated ester (IV), which is reduced with NaBH4 in trifluoroethanol/THF giving the carbinol (V). The deacetylation of (V) with hot hydrazine yields the 2-aminopiperidine (VI), which is treated with ethyl trifluoroacetate and DIEA in hot DMF to afford the trifluoroacetamide (VII). The debenzylation of the cyclic ketal of (VII) with H2 over Pd/C in methanol gives the protected intermediate (VIII), which is finally deprotected with 4N HCl in hot dioxane.