2-(1-tert-butoxycarbonylamino-ethyl)-6-{4-[1-tert-butoxycarbonyl-2-(tert-butyl-dimethyl-silanyloxy)-ethylcarbamoyl]-thiazol-2-yl}-nicotinic acid benzyl ester
2-(1-tert-butoxycarbonylamino-ethyl)-6-{4-[1-tert-butoxycarbonyl-2-(tert-butyl-dimethyl-silanyloxy)-ethylthiocarbamoyl]-thiazol-2-yl}-nicotinic acid benzyl ester
2-(1-tert-butoxycarbonylamino-ethyl)-6-[4-(1-tert-butoxycarbonyl-2-hydroxy-ethylthiocarbamoyl)-thiazol-2-yl]-nicotinic acid benzyl ester
2-(1-tert-butoxycarbonylamino-ethyl)-6-[4-(1-tert-butoxycarbonyl-2-hydroxy-ethylthiocarbamoyl)-thiazol-2-yl]-nicotinic acid benzyl ester
t-butyl (4S)-2-(2-{3-benzyloxycarbonyl-2-[(1R)-1-t-butoxycarbonylaminoethyl]pyridin-6-yl}-1,3-thiazol-4-yl)-4,5-dihydro-1,3-thiazole-4-carboxylate