Preparation and Reduction of Hexahydro[2.2]paracyclophane.

Hexahydro[2.2]paracyclophane (6) and related compounds were prepared from the extrusion of sulfur dioxide from 2,11-dithia-4,5,6,7,8,9-hexahydro[3.3]paracyclophane 2,2,11,11-tetraoxide (9) by either the Ramberg-Backlund reaction or a flash pyrolysis. Compound 6 is the first cyclophane to contain both a benzene ring and a cyclohexane ring. Birch reduction of compound 6 gave a diene containing two double bonds in the same ring, which is different from the dienes obtained from the catalytic hydrogenation of [2.2]paracyclophane.