(3S)-3-[(1S)-1-(benzoyloxy)ethyl]azetidin-2-one

ethyl 4-((2R,3S)-3-((R)-1-((tert-butyldimethylsilyl)oxy)ethyl)-4-oxoazetidin-2-yl)but-2-ynoate

(5R,6S)-6-<(1R)-hydroxyethyl>-2-(2-aminoethyl)-2-penem-3-carboxylic acid

(2aS,2bS,5aS,6R)-2-Eth-(Z)-ylidene-2b-methyl-1,4-dioxo-octahydro-3-oxa-6a-aza-cyclobuta[a]pentalene-6-carboxylic acid benzyl ester

4-nitrobenzyl (4-{[(2R,3S)-3-((1R)-1-{[tert-butyl(dimethyl)silyl]oxy}ethyl)-4-oxoazetidin-2-yl]acetyl}-2-chlorophenyl)acetate