18-(4-Fluoro-1,3-dihydroisoindole-2-carbonyl)oxy-14-[(2-methylpropan-2-yl)oxycarbonylamino]-11-(2-nitrophenyl)sulfonyl-2,15-dioxo-3,11,16-triazatricyclo[14.3.0.04,6]nonadec-7-ene-4-carboxylic acid