The Highly Efficient Oxidation of Olefins, Alcohols, Sulfides and Alkanes with Heteroaromatic N-Oxides Catalyzed by Ruthenium Porphyrins

The oxygen atom transfer reactions from 2.6-disubstituted pyr~dine Noxides to olefins, ally1 or benzyl alcohols and sulfides were efficiently catalyzed by ruthenium porphyrins, and these substrates were convened into epoxides, aldehydes and sulfoxides, respectively, with high selectivity These oxidat~ons also proceeded using other heteroaromatic N-oxldes, such as pyrazine N-oxides, as oxidants.The catalytic activity of ruthenium porphyrin complexes was enhanced by the addition of a small amount of HCI or HBr In the presence of these acids, the oxidat~ons of alkanes or aliphatic alcohols with 2.6-dichloropyridine N-oxides were also efficiently catalyzed by ruthenium porphyrin complexes, and alcohols or ketones were afforded as oxidation products with high selectivity In the hydroxylat~on of adamantane, ruthenium polphyrins work very efficiently as catalysts, giving a turnover number of up to 120000.This system offers pract~cal advantages, such as mild conditions, tractability of ox~dants and easy overall procedures.In the case of the reactions with HCI or HBr, one possibihty in the reactton mechan~sm is that the activity of ruthenium porphyrins is enhanced in pan by the coordmat~on of CI-or B r as axial hgands.