title: Dichlororuthenium(IV) complex of meso-tetrakis(2,6-dichlorophenyl)porphyrin: active and robust catalyst for highly selective oxidation of arenes, unsaturated steroids, and electron-deficient alkenes by using 2,6-dichloropyridine N-oxide.
abstract: [Ru(IV)(2,6-Cl2tpp)Cl2], prepared in 90 % yield from the reaction of [Ru(VI)(2,6-Cl2tpp)O2] with Me3SiCl and structurally characterized by X-ray crystallography, is markedly superior to [Ru(IV)(tmp)Cl2], [Ru(IV)(ttp)Cl2], and [Ru(II)(por)(CO)] (por=2,6-Cl2tpp, F20-tpp, F28-tpp) as a catalyst for alkene epoxidation with 2,6-Cl2pyNO (2,6-Cl2tpp=meso-tetrakis(2,6-dichlorophenyl)porphyrinato dianion; tmp=meso-tetramesitylporphyrinato dianion; ttp=meso-tetrakis(p-tolyl)porphyrinato dianion; F20-tpp=meso-tetrakis(pentafluorophenyl)porphyrinato dianion; F28-tpp=2,3,7,8,12,13,17,18-octafluoro-5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato dianion). The "[Ru(IV)(2,6-Cl2tpp)Cl2]+2,6-Cl2pyNO" protocol oxidized, under acid-free conditions, a wide variety of hydrocarbons including 1) cycloalkenes, conjugated enynes, electron-deficient alkenes (to afford epoxides), 2) arenes (to afford quinones), and 3) Delta5-unsaturated steroids, Delta4-3-ketosteroids, and estratetraene derivatives (to afford epoxide/ketone derivatives of steroids) in up to 99 % product yield within several hours with up to 100 % substrate conversion and excellent regio- or diastereoselectivity. Catalyst [Ru(IV)(2,6-Cl2tpp)Cl2] is remarkably active and robust toward the above oxidation reactions, and turnover numbers of up to 6.4x10(3), 2.0x10(4), and 1.6x10(4) were obtained for the oxidation of alpha,beta-unsaturated ketones, arenes, and Delta5-unsaturated steroids, respectively.
authors.affiliation: Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: Jun-Long
authors.initials: JL
authors.lastname: Zhang
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Che
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D004583:Electrons; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D017975:Ruthenium Compounds / Q000737:chemistry*; D013256:Steroids / Q000737:chemistry*
chemical_list: C512313:2,6-dichloropyridine N-oxide; D000475:Alkenes; D008024:Ligands; D010087:Oxides; D011166:Porphyrins; D011725:Pyridines; D017975:Ruthenium Compounds; D013256:Steroids; D001554:Benzene