tert-butyl (3S,5R)-5-methyl-2-oxotetrahydro-2H-pyran-3,5-diyldicarbamate

methyl (2S,4R)-2,4-bis((tert-butoxycarbonyl)amino)-5-hydroxy-4-methylpentanoate

(2S,6S,E)-methyl 2-(benzyloxycarbonylamino)-6-(tert-butyl-diphenylsilyloxy)-4-methylhept-4-enoate

(2S,6S,E)-methyl 2-((benzyloxycarbonyl)(tert-butoxycarbonyl)amino)-6-(carbamoyloxy)-4-methylhept-4-enoate

(2S,4R,E)-methyl 2-((benzyloxycarbonyl)(tert-butoxycarbonyl)amino)-4-(tert-butoxycarbonylamino)-4-methylhept-5-enoate