Development ot highly selective oxygenation by oxygenase-model metal-oxygen active species and clarification of the mechanisms of selectivity control

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Highly selective oxygenations by nonheme metal-oxygen species were developed and mechanisms of the control of selectivity were studied spectroscopically.Selective intradiol oxygenation of catechols by iron(III) complexes has been extensively studied. We have developed the selective oxygenation of chlorocatechols. Products include dehydrochlorinated products, that opens the new process for the dechlorination of chloroaromatics which are environmental pollutant. The model intermediate complexes, chlorocatecholatoiron complexes have been isolated. Their configurational and electronic structures were analyzed by XAFS, magnetic susceptibility, EPR, electronic absorption spectra. It was indicated that the complexes should be represented by lron(II)-semiquinonate rather than lron(III)-catecholate complexes. Another dioxygenase model reactions studied are lipoxygenase model which oxygenates linoleic acid, tyrosine hydroxylase model which hydroxylates t-butylphenol to give o-catechol, and a-keto acid dependent oxygenase which oxygenates alkenes to give epoxides and alkanes to give alcohols. Mechanistic investigations were performed in addition to the synthetic works. These reactions are under further studies to develop good catalytic oxygenation systems and to get mechanistic information for enzymatic oxygenations.