Dibenzo chrysene, synthesis

Methods for the synthesis of the biologically active dihydrodiol and diol epoxide metabolites of both carcinogenic and noncarcinogenic polycyclic aromatic hydrocarbons are reviewed. Four general synthetic routes to the trans-dihydrodiol precursors of the bay region anti and syn diol epoxide derivatives have been developed. Syntheses of the oxidized metabolites of the following hydrocarbons via these methods are described benzo(a)pyrene, benz(a)anthracene, benzo-(e)pyrene, dibenz(a,h)anthracene, triphenylene, phen-anthrene, anthracene, chrysene, benzo(c)phenanthrene, dibenzo(a,i)pyrene, dibenzo(a,h)pyrene, 7-methyl-benz(a)anthracene, 7,12-dimethylbenz(a)anthracene, 3-methylcholanthrene, 5-methylchrysene, fluoranthene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)-fluoranthene, and dibenzo(a,e)fluoranthene. 

Diels-Alder cycloaddition provides one of the most useful methods for the construction of polycyclic aromatic ring systems. With the use of maleic anhydride as dienophile, two additional carbon atoms may be fused to the bay region sites of some polycyclic arylenes to generate additional rings. For example, the first step in the synthesis of benzo[ghi]perylene 6 involves a Diels-Alder cycloaddition between perylene and maleic anhydride (Scheme 3.5) [19]. Aryne intermediates generated in situ also serve as dienophiles for Diels-Alder cycloadditions for example, reaction of 1,5-naphthadiyne (generated in situ from 2,6-dibromo-l,5-bis[(p-tolylsulfonyl)oxy] naphthalene with 2-methylisoindole forms an adduct which upon oxidation with m-chloroperbenzoic acid affords dibenzo[fe,k]chrysene 7 (Scheme 3.5) [20]. 

Fischer, E., Larsen,)., Christensen, ).B., Fourmigue, M., Madsen, H.G., and Harrit, N., Synthesis of new sulfur heteroaromatics isoelectronic with dibenzo[g,p]chrysene by photocyclization of thienyl- and phenyl-substituted ethenes, /. Org. Chem., 61, 6997, 1996. 

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