SYNTHESIS OF NON-K-REGION AND K-REGION TRANS-DIHYDRODIOLS OF BENZO[E]PYRENE

Syntheses of trans-9,10-dihydroxy-9,10-dihydrobenzo[e]pyrene (14b) and of trans-4, 5-dihydroxy-4, 5-dihydrobenzo[e]pyrene (17a) are described. The preparation of the non-K-region trans-dihydrodiol 14b proceeded via standard procedures from 9-oxo-9, 10, 11, 12-tetrahydrobenzo[e]pyrene (7), the synthesis of which is described. Intramolecular cyclization of methyl 4-pyrenylbutyrate (6) in HF produced primarily the undesired seven-membered ring ketone 8, but cyclization in hot polyphosphoric acid gave the desired ketone 7 in good yield. Evidence is presented that 8 is the kinetic product of cyclization and that 7 is the more stable isomer which is produced under conditions of thermodynamic control. The NMR spectrum of the non-K-region dihydrodiol 14b in acetone-d6 indicates that the hydroxyl groups adopt a predominantly quasi-diaxial conformation. The trans-K-region dihydrodiol 17a was prepared from benzo[e]pyrene [B(e)P] by a multistep procedure involving conversion of B(e)P to the cisdiol, oxidation to the quinone, and reduction of the quinone with KBH4. The trans-diol 17a easily oxidizes in the presence of air. © 1978, American Chemical Society. All rights reserved.