3,9-Diazabicyclo[3.3.1]non-6-ene-3,9-dicarboxylic acid,6-[[cyclopropyl[(3-methoxy-2-methylphenyl)methyl]amino]carbonyl]-7-[4-[2-[[(1,1-dimethylethyl)dimethylsilyl]oxy]ethyl]phenyl]-,bis(1,1-dimethylethyl) ester