The fission of methanol from the diastereomeric 2,5-dimethoxy-2,5-dimethyl-3,4-diphenylhexanes leads to products which are best explained in terms of restriction about the central carbon-carbon bond. As would be expected from its stable conformation the dd,ll diastereomer easily forms the 2,2,5,5-tetramethyl-3,4-diphenyltetrahydrofuran, but the meso diastereomer forms a tetrahydrofuran with difficulty. On the other hand the meso diastereomer readily undergoes Friedel-Crafts types of condensation leading in different media to either 3,3-dimethyl-1-isopropenyl-2-phenylindane, 3,3-dimethyl-1-isopropyl-2-phenylindene or 5,5,10,10-tetramethyl-4b,5,9b, 10-tetrahydroindeno[2,1-α]-indene. These indenes are the expected products from a consideration of the conformation of the meso-dimethoxydimethyldiphenylhexane which is most free from steric restriction.