9-chloro-4-methyl-13-oxa-4-azatetracyclo[12.4.0.0^{2,6}.0^{7,12}]octadeca-1(18),7,9,11,14,16-hexaene; but-2-enedioic acid

9-chloro-4-methyl-13-oxa-4-azatetracyclo[12.4.0.0^{2,6}.0^{7,12}]octadeca-1(18),7,9,11,14,16-hexaene; but-2-enedioic acid