. "(4R,5S,6S)-3-(Ethyl-methyl-thiocarbamoylsulfanyl)-6-((R)-1-hydroxy-ethyl)-4-methyl-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid" . "9b" . . . . . . . . . . .