SYNTHESIS OF FJORD REGION DIOL EPOXIDES AS POTENTIAL ULTIMATE CARCINOGENS OF DIBENZO[A,I]PYRENE

Dibenzo[a,l]pyrene (DB[a,l]P) is one of the strongest polynuclear arom atic hydrocarbon carcinogens known. This paper describes the synthesis of potential ultimate carcinogens of DB[a,l]P: anti- and hydroxy-13,1 4-epoxy-11,12,13,14-tetrahydroDB[a,l]P (DB-[a,l]P-11,12-diol-13,14-epo xides). The method employed is also useful for the preparation of key intermediates for the synthesis of 3,14-epoxy-11,12,13,14-tetrahydrobe nzo-[g]chrysene (BgC-11,12-diol-13,14-epoxide). Photochemical cyclizat ion of the appropriately substituted phenanthrylphenylethylenes provid ed 9-carbomethoxy-11-methoxyBgC (4) and 11-methoxyBgC (3). The former was converted by reduction, oxidation, one-carbon chain extension, and cyclization to 11-methoxy DB[a,l]P(7). Compounds 3 and 7 were convert ed by hydrolysis and oxidation to BgC-11,12-dione (10) and DB[a,l]P-11 ,12-dione(11), respectively. The diones are the precursors for the syn thesis of the corresponding diol epoxides. anti- and syn-DB[a,l)P-11,1 2-diol-13,14-epoxides 13 and 14 were prepared in 38% and 55% yields, r espectively, from 11. Both diol epoxides had predominantly pseudodiequ atorial hydroxyl groups, as seen in other sterically hindered diol epo xides.