methyl (33R,35S,91R,92R,5S,E)-5-(tert-butyl)-14,14-difluoro-4,7-dioxo-2,8,10-trioxa-6-aza-1(2,3)-quinoxalina-3(3,1)-pyrrolidina-9(1,2)-cyclopentanacyclotetradecaphan-12-ene-35-carboxylate