Donald M. Jerina

Bacterial dioxygenase-catalysed dihydroxylation and chemical resolution routes to enantiopure cis-dihydrodiols of chrysene

Biotransformation of the environmental pollutant chrysene 1 by resting cells of a mutant strain (B8/36) of the soil bacterium Sphingomonas yanoikuyae produces (+)-cis-3,4-dihydroxy-3,4-dihydrochrysene 4 which has been assigned (3S,4R) absolute configuration by stereochemical correlation with (-)-(3S,4R)-cis-3,4- dihydroxy-1,2,3,4-tetrahydrochrysene 6. Both cis-3,4-diol 6 and cis-1,2-dihydroxy-1,2,3,4- tetrahydrochrysene 12 are obtained in enantiopure form after chromatographic separation of the individual bis(2-methoxy-2-phenyl-2-trifluoromethylacetyl) (bis-MTPA) diastereoisomers of compound 6 and the MTPA diastereoisomers of bromohydrin 19, respectively, followed by hydrolysis. A new general synthetic route to cis-dihydrodiols, from the corresponding cis-tetrahydrodiol cyclic carbonates, is used to obtain both racemic and enantiopure forms of the bay-region diol 4, and the non-bay region diol 5. 1 H NMR and CD spectra of the cis- and trans-dihydrodiols of chrysene are described.

Synthesis and spontaneous racemization of benz[a]anthracene 3,4-oxide: photochemical oxygen-walk rearrangements of arene oxides of benz[a]anthracene and triphenylene to yield oxepines

Benz[a]anthracene 3,4-oxide 2, when synthesised from optically pure dibromo ester precursors, was found to have racemized spontaneously and was accompanied by anthra[2,1-b]oxepine 14. Photoisomerization of benz[a]anthracene 3,4-oxide 2, triphenylene 1,2-oxide 4 and benz[a]anthracene 1,2-oxide 5 proceeds via an oxygen-walk mechanism to yield anthra[2,1-b]oxepine 14, phenanthro[10,9-b]oxepine 16 and anthra[2,1-f]oxepine 17 respectively.