1-Azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, 3-[[(2-amino-4-pyrimidinyl)thio]methyl]-6-[(1R)-1-hydroxyethyl]-4-methyl- 7-oxo-, 1-[[(cyclohexyloxy)carbonyl]oxy]ethyl ester, (4S,5R,6S)-