7-Meth-oxy-penta-cyclo-[5.4.0.0(2,6).0(3,10).0(5,9)]undec-ane-8,11-dione.

The structure of 7-meth-oxy-penta-cyclo-[5.4.0.0(2,6).0(3,10).0(5,9)]undecane-8,11-dione, C(12)H(12)O(3), at 150†K has monoclinic (P2(1)/c) symmetry. The penta-cyclo-undecane cage compound is composed of four five-membered rings, a planar four-membered ring and a six-membered ring in a boat conformation fused into a closed strained-cage framework. All of the five-membered rings adopt an envelope conformation.