Diethyl 1,8-bis-(4-methyl-phen-yl)-11-oxatricyclo-[6.2.1.0(2,7)]undeca-2,4,6-triene-9,10-dicarboxyl-ate.

The title compound, C30H30O5, is the Diels-Alder adduct from 1,3-diphenyl-benzo[c]furan and diethyl maleate. The mol-ecule comprises a fused tricyclic system containing two five-membered rings, which are in envelope conformations with the O atom at the flap, and a six-membered ring adopting a boat conformation. The dihedral angle between the 4-methyl-phenyl substituents in the 1- and 8-positions is 62.1 (1)°. The ethyl group of one ester group and the eth-oxy group of the other ester group are disordered over two sets of sites, with occupancy ratios of 0.43 (2):0.57 (2) and 0.804 (7):0.196 (7), respectively. In the crystal, inversion dimers are formed through pairs of C-H⋯O inter-actions.