合成路线1

The reaction of N-(benzyloxycarbonyl)-L-asparagine (I) with bis(trifluoroacetyl)iodobenzene (BTI) in DMF/water gives 3-amino-2(S)-(benzyloxycarbonylamino)propionic acid (II), wehich is protected at the amino group with tert-butoxycarbonyl anhydride yielding carbamate (III). The esterification of (III) with ethanol WSC and DMAP affords the expected ethyl ester (IV), which is selectively deprotected with methanesulfonic acid in acetonitrile providing 3-amino-2-(benzyloxycarbonylamino)propionic acid ethyl ester (V). The condensation of (V) with N-(tert-butoxycarbonyl)-beta-alanine (VI) by means of HOBT, WSC and triethylamine in DMF gives the protected propionamidopropionic ester (VII), which is selectively deprotected by hydrogenation with H2 over Pd/C in ethanol/ethyl acetate giving the 2-aminopropionic ester (VIII). The condensation of (VIII) with 4-ethylbenzenesulfonyl chloride (IX) by means of triethylamine in dichloromethane yields the sulfonamide (X), which is deprotected with methanesulfonic acid as before afording intermediate (XI) with a free amino group, which is condensed with 4-(tert-butoxycarbonylamino)benzoic acid (XII) by means of HOBT and WSC in DMF providing the fully protected target compound (XIII).