(2R,3aR,6R,7R,7aR)-2-((S)-2-tert-Butoxycarbonylamino-2-methoxycarbonyl-ethyl)-6,7-dihydroxy-hexahydro-furo[3,2-b]pyran-2-carboxylic acid methyl ester

(S)-4-((2R,3R,4S,5R)-4,5-Bis-benzyloxy-3-hydroxy-tetrahydro-pyran-2-ylmethyl)-2-tert-butoxycarbonylamino-pent-4-enoic acid methyl ester

(S)-4-((2R,3S,4S,5R)-4,5-Bis-benzyloxy-3-hydroxy-tetrahydro-pyran-2-ylmethyl)-2-tert-butoxycarbonylamino-pent-4-enoic acid methyl ester

(2R,3aR,6R,7R,7aS)-6,7-Bis-benzyloxy-2-((S)-2-tert-butoxycarbonylamino-2-methoxycarbonyl-ethyl)-hexahydro-furo[3,2-b]pyran-2-carboxylic acid methyl ester

(2S,3aR,6R,7R,7aS)-6,7-Bis-benzyloxy-2-((S)-2-tert-butoxycarbonylamino-2-methoxycarbonyl-ethyl)-hexahydro-furo[3,2-b]pyran-2-carboxylic acid methyl ester