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

The title compound, C28H26O5, is the Diels-Alder adduct from 1,3-diphenyl-benzo[c]furan and diethyl maleate. The mol-ecule comprises of 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 phenyl substituents in the 1,8-positions is 55.1 (1)°. The ethyl groups are disordered over two sets of sites, with occupancy ratios of 0.648 (9):0.352 (9) and 0.816 (1):0.184 (1). In the crystal, pairs of C-H⋯π inter-actions link the mol-ecules into inversion dimers.