Cyanic acid,3-[5-[1-[5-[5-[1-(3-cyanatophenyl)-2,5-dioxo-3-pyrrolidinyl]-1,3,3a,4,5,9b-hexahydro-5-methyl-1,3-dioxo-2H-benz[e]isoindol-2-yl]-2-methylphenyl]-2,5-dioxo-3-pyrrolidinyl]-1,3,3a,4,5,9b-hexahydro-5-methyl-1,3-dioxo-2H-benz[e]isoindol-2-yl]pheny