Spiro­[cyclo­pentane-1,11′-hexa­cyclo[7.6.0.01,6.06,13.08,12.010,14]penta­deca­ne]-7′,15′-dione

An unusual rearrangement of spiro cage dione to a tris­homocubane derivatives is reported by acid-catalysed rearrangement with the aid of BF3·OEt2 in benzene (solvent) reflux conditions. Here, the mol­ecular structure of cage mol­ecule C19H22O2 (major product) consists of five-membered rings, which adopt an envelope conformation and six-membered rings adopt a chair or boat conformation. The Cremer & Pople puckering parameters of all four six-membered rings are calculated.