The preparation of dihydrodiols from 7-methylbenz[a]-anthracene

The products formed when the carcinogenic polycyclic hydrocarbon 7-methylbenz[a] anthracene is oxidized with an ascorbic acid-ferrous sulphate mixture have been investigated. All 5 possible dihydrodiols were formed and the isolation of the 3 non-K-region dihydrodiols, trans-1,2-dihydro-1,2-dihydroxy-7-methylbenz[a]anthracene, trans-3,4-dihydro-3,4-dihydroxy-7-methylbenz[a] anthracene and trans-8,9-dihydro-8,9-dihydroxy-7-methylbenz[a] anthracene is described. The purification of the dihydrodiols was carried out by thin-layer (TLC) followed by preparative high pressure liquid chromatography (HPLC). The ultra-violet, spectral and nuclear magnetic resonance (NMR) characteristics of the dihydrodiols are reported and the data used to assign the proposed structures. An explanation for the unusual preferred conformation which the 8,9-dihydrodiol adopts is advanced.