Herein, we report the divanadium-substituted phosphotungstate (I )-catalyzed oxidative functional group transformations such as (1) epoxidation of alkenes including electron-deficient ones, (2) chemo- and regioselective hydroxylation of alkanes and arenes, and (3) oxidative bromination of alkenes, alkynes, and aromatics with Br- as a bromo source.In the presence of I , various kinds of electron-deficient alkenes with acetate, ether, carbonyl, and chloro groups at the allylic positions could chemoselectively be oxidized to the corresponding epoxides in high yields with only an equimolar amount of H2O2 with respect to the substrates. Even acrylonitrile and methacrylonitrile could be epoxidized without formation of the corresponding amides. In addition, I  could efficiently (=10 min) catalyze epoxidation of various kinds of terminal, internal, and cyclic alkenes with H2O2 under the stoichiometric conditions.Compound I  could catalyze the oxidation of various kinds of cyclic alkanes with H2O2. The oxidation of cyclic alkanes selectively proceeded to afford the corresponding alcohols (=98% selectivity). Acyclic n-hexane was also hydroxylated to the corresponding alcohols with =96% selectivity. Notably, the present system also showed the unusual regioselectivity to the secondary alcohols for the oxidation of some cycloalkanes with both secondary and tertiary C-H bonds. Compound I  also showed high catalytic activity for hydroxylation of various kinds of aromatics to phenols with aqueous H2O2. The present system showed specific regioselectivities to para-phenols for mono-substituted benzenes. In addition, alkylaromatics with reactive primary, secondary, and tertiary aromatic side-chain sp3 C�H bonds could chemoselectively be hydroxylated without significant formation of the side-chain oxygenated products.The I -catalyzed system could be applied to oxidative bromination of various substances. Compound I  showed high catalytic activity for H2O2-based oxidative bromination of various alkenes, alkynes, and aromatics under very mild reaction conditions.

Selective oxidation of hydrocarbons with aqueous hydrogen peroxide catalyzed by divanadium-substituted polyoxometalates

248th National Meeting (2014)

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