Regio- and stereo-selective dioxygenase-catalysed cis-dihydroxylation of fjord-region polycyclic arenes

Bacterial dioxygenase-catalysed cis-dihydroxylation of the tetracyclic arenes benzo[c]phenanthrene 2, and the isosteric compounds benzo[b]naphtho[1,2-d]furan 8, and benzo[b]naphtho[1,2-d]thiophene 9, has been found to occur exclusively at fjord-region bonds. The resulting cis-dihydrodiols 7, 10 and 11 were found to be enantiopure and of similar absolute configuration. cis-Dihydroxylation was also observed in the pseudo-fjord region of the 8,9,10,11-tetrahydro-precursors (12 and 13) of benzo[b]naphtho[1,2-d]furan 8, and benzo[b]naphtho[1,2-d]thiophene 9, to yield the corresponding enantiopure hexahydro cis-diols 14 and 15. A novel tandem cis-dihydroxylation and bis-desaturation of the tetrahydro-substrate, tetrahydrobenzo[b]naphtho[1,2-d]thiophene 13, catalysed by biphenyl dioxygenase, was found to yield the fjord-region cis-dihydrodiol 17 of benzo[b]naphtho[1,2-d]thiophene 9.