SYNTHESIS OF KETONE AND ALCOHOL DERIVATIVES OF METHYLENE-BRIDGED POLYARENES, POTENTIALLY NEW CLASSES OF ACTIVE METABOLITES OF CARCINOGENIC HYDROCARBONS

Methods for the syntheses of bridge ketone and alcohol derivatives of methylene-bridged polyarenes from the parent hydrocarbons are described. The polyarenes investigated include 4H-cyclopenta[def]phenanthrene (1a), fluorene (2a), 7H-benzo[c]fluorene (3a), 4H-cyclopenta[def]chrysene (4a), 11H-Benz[bc]aceanthrylene (5a), 10H-indeno[1,2,7,7a-bcd]pyrene (6a), 11H-dibenzo[bc,l]aceanthrylene (7a), 4H-fluoreno[4,4a,4b,5-abc]anthracene (8a), and 7H-dibenzo[a,g]fluorene (9a). The bridge ketone derivatives are most efficiently synthesized via treatment of the parent hydrocarbons with n-butyllithium and reaction of the resulting anionic intermediates with molecular oxygen. The direct formation of ketones rather than the expected hydroperoxides from reaction of the bridge anions With O2 presumably involves intra- or intermolecular abstraction of a proton from the benzylic site of the intermediate by the peroxy anion leading to loss of hydroxide ion with formation of a carbonyl group. Yields are generally high except in the cases of 1a and 4a; the former affords as the principal product a dimeric alcohol arising from reaction of the anion of 1a with the corresponding ketone lb. The related bridge alcohols am readily obtained in yields of 75-95% by reduction of the crude products from the preceding oxidations with NaBH4.