4,5,6,9-Tetra­methoxy-11-phenyl-10-oxa-11-aza­tri­cyclo­[7.2.2.02,7]­trideca-2(7),3,5,12-tetraen-8-one

The crystal structure of the adduct, C21H21NO2, of tetra­methyl­purpurogallin with nitro­so­benzene is reported. The compound exhibits a [3.2.2] bicyclic system corresponding to two seven-membered rings and one six-membered ring in distorted chair, boat and twist–boat conformations, respectively. One intramolecular and two intermolecular hydrogen bonds direct the packing and stabilize the mol­ecule.