ethyl 4-(1-benzyloxycarbonyl-4-piperidyl)-2-chlorobutyrate

4-[(S)-3-((S)-9-Benzyloxycarbonylmethyl-8-oxo-6,7,8,9-tetrahydro-5-oxa-9-aza-benzocyclohepten-7-ylamino)-3-ethoxycarbonyl-propyl]-piperidine-1-carboxylic acid benzyl ester

4-[(R)-3-((S)-9-Benzyloxycarbonylmethyl-8-oxo-6,7,8,9-tetrahydro-5-oxa-9-aza-benzocyclohepten-7-ylamino)-3-ethoxycarbonyl-propyl]-piperidine-1-carboxylic acid benzyl ester

ethyl 5-(1-benzyloxycarbonyl-4-piperidyl)-2-oxovalerate

benzyl 3(S)-[4-(1-benzyloxycarbonyl-4-piperidyl)-1(R)-ethoxycarbonylbutyl]amino-4-oxo-2,3,4,5-tetrahydro-1,5-benzoxazepine-5-acetate