O-benzyl-N-<(4S,7S)-6-benzyloxycarbonyl-1-oxo-5-oxa-2,6-diazaspiro<3.5>nonane-7-carbonyl>-L-threonine benzyl ester

N-((3S,6S)-6-aminomethyl-2-benzyloxycarbonyl-6-carboxyperhydro-1,2-oxazine-3-carbonyl)-O-benzyl-L-threonine benzyl ester

N-<(3S,6S)-6-benzhydryloxycarbonyl-2-benzyloxycarbonyl-6-<(chloroacetamido)methyl>perhydro-1,2-oxazine-3-carbonyl>-O-benzyl-L-threonine benzyl ester