Dibenzo trans-anti

Hydrogenation of the isomer of dibenzo [18] crown-6, originally synthesised by Pedersen using H2/Pd, gives the saturated dicyclohexyl[18]crown-6. Excluding enantiomers, this material has five isomers, of which the cis-syn-cis isomer (isomer A) is shown below. The other isomers are called cis-anti-cis, trans-syn-trans, trans-anti-trans and cis-trans. Draw these isomers and assign the names to the structures. 

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. 

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