Molecular structure of (+/-)-7,8,9,10-tetrahydroxy-7,8,9,10-tetrahydrobenzo(a)pyrene determined by x-ray crystallography.

The molecular structure of a tetrahydrotetrol that is formed by hydrolysis of (+/-)-7 alpha, 8 beta-dihydroxy-9 beta, 10 beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, has been determined by X-ray crystallographic methods. The relative orientations of the four hydroxyl groups of the racemic tetrahydrotetrol (7 alpha, 8 beta, 9 beta, 10 alpha) indicate that the tetrahydrotetrol was formed by the trans opening of the epoxide ring of the diol-oxide. The hydroxyl groups at positions 7 and 8 adopt a diequatorial conformation, while those at positions 9 and 10 adopt a diaxial conformation. Several other geometric features are discussed.