tert-butyl 3(S)-[6(1-benzyloxycarbonyl-4-piperidyl)-1(R)-ethoxycarbonylhexyl]amino-4-oxo-2,3,4,5 -tetrahydro-1,5-benzoxazepine-5-acetate

4-[(S)-6-((S)-9-tert-Butoxycarbonylmethyl-8-oxo-6,7,8,9-tetrahydro-5-oxa-9-aza-benzocyclohepten-7-ylamino)-6-ethoxycarbonyl-hexyl]-piperidine-1-carboxylic acid benzyl ester

benzyl 4-(6-ethoxy-6-oxohexyl)piperidine-1-carboxylate

ethyl 6-(1-benzyloxycarbonyl-4-piperidyl)-2-oxohexanoate

ethyl 7-(1-benzyloxycarbonyl-4-piperidyl)-2-oxoheptanoate