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

(2S,5R,6S)-6-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-3,3-dimethyl-4,4,7-trioxo-4λ6-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid benzyl ester

(2S,5R,6R)-6-[(R)-1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-3,3-dimethyl-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid benzyl ester

4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid,6-(1-hydroxyethyl)-3,3-dimethyl-7-oxo-6-(phenylseleno)-, phenylmethylester, [2S-[2a,5a,6b,6(S*)]]-

methyl 2-((2R,3S)-3-((S)-1-((tert-butyldimethylsilyl)oxy)ethyl)-2-(methylthio)-4-oxoazetidin-1-yl)-3-methylbut-2-enoate

(2S,5R,6S)-6-Bromo-6-[1-(tert-butyl-dimethyl-silanyloxy)-ethyl]-3,3-dimethyl-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid methyl ester

methyl (2S,5R,6S)-6-bromo-6-((R)-1-hydroxyethyl)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate

(3S,4R)-3-[(R)-1-Hydroxyethyl]-1-(1-methoxycarbonyl-2-methylprop-1-enyl)-4-methylthioazetidin-2-one

benzyl (2S,5R,6R)-6-<(R)-1-(t-butyldimethylsilyloxy)ethyl>penicillanate 1,1-dioxide

(5R)-6ξ-((R)-1-hydroxy-ethyl)-3,3-dimethyl-7-oxo-(5rH)-4-thia-1-aza-bicyclo[3.2.0]heptane-2c-carboxylic acid benzyl ester

benzyl (2S,5R,6S)-6-<(R)-1-hydroxyethyl>-6-(phenylseleno)penicillanate

benzyl (2S,5R,6R)-6-<(R)-1-hydroxyethyl>penicillanate