1-Azabicyclo[3.2.0]hept-2-ene-2-carboxylicacid,3-[[5-[(2-fluoroethoxy)methyl]-3-pyrrolidinyl]thio]-6-(1-hydroxyethyl)-4-methyl-7-oxo-,[4R-[3(3S*,5S*),4a,5b,6b(R*)]]-