(2R,3aR,6S,7R,7aR)-2-[(2S)-2-amino-3-hydroxy-3-oxopropyl]-6-hydroxy-7-methylamino-3,3a,5,6,7,7a-hexahydrofuro[4,5-b]pyran-2-carboxylic acid
(2R,3aR,6S,7R,7aR)-2-[(2S)-2-amino-3-hydroxy-3-oxo-propyl]-6-hydroxy-7-methylamino-3,3a,5,6,7,7a-hexahydrofuro[4,5-b]pyran-2-carboxylic acid
(2R,3aR,6S,7R,7aR)-2-[(2S)-2-amino-3-hydroxy-3-keto-propyl]-6-hydroxy-7-methylamino-3,3a,5,6,7,7a-hexahydrofuro[4,5-b]pyran-2-carboxylic acid