Dimethyl 7-meth-oxy-tetra-cyclo-[6.4.0.0(2,4).0(3,7)]dodeca-1(12),5,8,10-tetra-ene-3,4-dicarboxyl-ate.

The title compound, C(17)H(16)O(5), is a previously unreported substituted semibulvalene cage compound (that is, a tricyclic hydro-carbon formed from one cyclo-propane and two cyclo-pentene rings which also has one double bond fused to a benzene ring). It has one meth-oxy substituent attached to the bridgehead C atom that links only the two cyclo-pentene rings and two methyl carboxyl-ate groups located on the C atom shared by all three non-benzene rings and that shared only between the cyclo-propane and the cyclo-pentene rings. The stereochemistry of the two enanti-omers (racemate) that assemble in each unit cell is RRRS and SSSR.