(4R,5S,6S)-3-[(2R,3R)-2-(aminomethyl)oxolan-3-yl]sulfanyl-6-(1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid
(4R,5S,6S)-3-[(2R,3R)-2-(aminomethyl)tetrahydrofuran-3-yl]sulfanyl-6-(1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid
(4R,5S,6S)-3-[[(2R,3R)-2-(aminomethyl)-3-tetrahydrofuranyl]thio]-6-(1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid
(4R,5S,6S)-3-[[(2R,3R)-2-(aminomethyl)tetrahydrofuran-3-yl]thio]-6-(1-hydroxyethyl)-7-keto-4-methyl-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid