(R)-4-nitrobenzyl 2-diazo-4-((2R,3S)-3-((R)-1-hydroxyethyl)-4-oxoazetidin-2-yl)-3-oxopentanoate; (3S,4R)-3-[(1R)-1-Hydroxyethyl]-4-[(1R)-1-methyl-3-diazo-3-(p-nitrobenzyloxycarbonyl)-2-oxopropyl]azetidin-2-one
(R)-4-nitrobenzyl 2-diazo-4-((2R,3S)-3-((R)-1-hydroxyethyl)-4-oxoazetidin-2-yl)-3-oxopentanoate; (3S,4R)-3-[(1R)-1-Hydroxyethyl]-4-[(1R)-1-methyl-3-diazo-3-(p-nitrobenzyloxycarbonyl)-2-oxopropyl]azetidin-2-one