KETONE PYRAMIDALIZATION IN A TETRACYCLIC PERPENDICULAR ENONE DERIVATIVE

endo,exo-11,11-Dimethoxytetracyclo[6.2.1.1(3,6).0(2,&)]dodeca-9-en-12-one (1), C14H18O3, M(r) = 234.30, monoclinic, P2(1)/n, a = 14.113 (2), b = 10.032 (1), c = 17.086 (2) angstrom, beta = 103.55 (1)degrees, V = 2351.74 angstrom3, Z = 8, D(x) = 1.323 g cm-3, lambda(Cu Kalpha) = 1.54056 angstrom, mu = 7.038 cm-1, F(000) = 1008, T = 133 K, R = 0.0433 and wR = 0.0435 for 4255 unique reflections. The molecule contains a norbornanone unit fused to a substituted norbornene. The ring C atom of the ketone is significantly pyramidalized. Possible factors contributing to this deformation include incipient nucleophilic attack by the pi electrons at the carbonyl C atom, polarization of the pi system, relief of bond-angle compression, and steric effects.