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

(3R,4R)-3-<(R)-1-(tert-butyldimethylsilyloxy)ethyl>-4-methylsulfonyl-2-azetidinone

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

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

p-nitrobenzyl 2-<(3S,4R)-3-<(1R)-(tert-butyldimethylsiloxy)ethyl>-4-(4-p-nitrobenzyloxycarbonylaminobutyrylthio)-2-oxoazetidin-1-yl>-2-triphenylphosphoranylideneacetate