(3aS,6R,7R,7aR)-1-methyl-6-(2-oxopropyl)-7-(triethylsilyloxy)hexahydropyrano[4,3-d]oxazol-2-one

methyl (2S,3a'S,6'R,7'R,7a'S)-2-methoxycarbonylamino-4[[1'-methyl-2'-oxo-7'-(triethylsilyloxy)hexahydropyrano[4,3-d]oxazol-6'-yl]methyl]pent-4-enoate

ethyl (4S,4'S,5'S,Z)-4-[5'-(tertbutyldimethylsilyloxy)methyl-3'-methyl-2'-oxooxazolidin-4'-yl]-4-(tert-butyldimethylsilyloxy)but-2-enoate

(S)-4-((3aS,6R,7R,7aS)-7-Hydroxy-1-methyl-2-oxo-hexahydro-pyrano[4,3-d]oxazol-6-ylmethyl)-2-methoxycarbonylamino-pent-4-enoic acid methyl ester