allyl (5R,6S)-2-<<(methylsulfonyl)oxy>methyl>-6-<(R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>penem-3-carboxylate

allyl (5R,6S)-2-<((2S,4R)-4-acetoxy-1-prolinamido)methyl>-6-<(R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>penem-3-carboxylate

allyl (5R,6S)-2-<<N-methyl-N-(2R)-(2-propionamido)amino>methyl>-6-<(R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>penem-3-carboxylate

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

allyl (5R,6S)-2-<((2S)-1-prolinamido)methyl>-6-((R)-1-hydroxyethyl)penem-3-carboxylate

allyl (5R,6S)-2-<<N-methyl-N-<N'-(2-acetamido)-2-acetamido>amino>methyl>-6-<(R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>penem-3-carboxylate

(5R,6S)-3-{[((S)-1-Carbamoyl-2-phenyl-ethyl)-methyl-amino]-methyl}-6-((R)-1-hydroxy-ethyl)-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid allyl ester

allyl (5R,6S)-2-<<N-methyl-N-(2S)-(2-propionamido)amino>methyl>-6-<(R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>penem-3-carboxylate

allyl (5R,6S)-2-<((2S,4R)-4-(acetyloxy)-1-prolinamido)methyl>-6-((R)-1-hydroxyethyl)penem-3-carboxylate

allyl (5R,6S)-2-<((2S,4S)-4-hydroxy-1-prolinamido)methyl>-6-<(R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>penem-3-carboxylate

allyl (5R,6S)-2-<<(2S,4R)-4-<<N-(trichloroacetyl)carbamoyl>oxy>-1-prolinamido>methyl>-6-<(R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>penem-3-carboxylate

(5R,6S)-3-((2R,4S)-2-Carbamoyl-4-hydroxy-pyrrolidin-1-ylmethyl)-6-((R)-1-hydroxy-ethyl)-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid allyl ester

allyl (5R,6S)-2-<<(2S)-2-(methoxycarbonyl)pyrrolidin-1-yl>methyl>-6-((R)-1-hydroxyethyl)penem-3-carboxylate

(5R,6S)-3-({[(Carbamoylmethyl-carbamoyl)-methyl]-methyl-amino}-methyl)-6-((R)-1-hydroxy-ethyl)-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid allyl ester