1-Azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid,3-[[(3S,5S)-5-[[(2,6-diamino-4-pyrimidinyl)thio]methyl]-3-pyrrolidinyl]thio]-6-[(1R)-1-hydroxyethyl]-4-methyl-7-oxo-, (4R,5S,6S)-