Arylruthenium(III) Porphyrin-Catalyzed C-H Oxidation and Epoxidation at Room Temperature and [RuV(Por)(O)(Ph)] Intermediate by Spectroscopic Analysis and Density Functional Theory Calculations.

The development of highly active and selective metal catalysts for efficient oxidation of hydrocarbons and identification of the reactive intermediates in the oxidation catalysis are long-standing challenges. In the rapid hydrocarbon oxidation catalyzed by ruthenium(IV) and -(III) porphyrins, the putative Ru(V)-oxo intermediates remain elusive. Herein we report that arylruthenium(III) porphyrins are highly active catalysts for hydrocarbon oxidation. Using catalyst [RuIII(TDCPP)(Ph)(OEt2)] (H2TDCPP = 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin), the oxidation of C-H bonds of various hydrocarbons with oxidant m-CPBA at room temperature gave alcohols/ketones in up to 99% yield within 1 h; use of [ nBu4N]IO4 as a mild alternative oxidant avoided formation of lactone from cyclic ketone in C-H oxidation, and the catalytic epoxidation with up to 99% yield and high selectivity (no aldehydes as side product) was accomplished within 5 min. UV-vis, electrospray ionization-mass spectrometry, resonance Raman, electron paramagnetic resonance, and kinetic measurements and density functional theory calculations lend evidence for the formation of Ru(V)-oxo intermediate [RuV(TDCPP)(O)(Ph)].

N-Heterocyclic Carbene Iron(III) Porphyrin-Catalyzed Intramolecular C(sp3 )-H Amination of Alkyl Azides.

Metal-catalyzed intramolecular C-H amination of alkyl azides constitutes an appealing approach to alicyclic amines; challenges remain in broadening substrate scope, enhancing regioselectivity, and applying the method to natural product synthesis. Herein we report an iron(III) porphyrin bearing axial N-heterocyclic carbene ligands which catalyzes the intramolecular C(sp3 )-H amination of a wide variety of alkyl azides under microwave-assisted and thermal conditions, resulting in selective amination of tertiary, benzylic, allylic, secondary, and primary C-H bonds with up to 95 % yield. 14 out of 17 substrates were cyclized selectively at C4 to give pyrrolidines. The regioselectivity at C4 or C5 could be tuned by modifying the reactivity of the C5-H bond. Mechanistic studies revealed a concerted or a fast re-bound mechanism for the amination reaction. The reaction has been applied to the syntheses of tropane, nicotine, cis-octahydroindole, and leelamine derivatives.

C,O-Chelated BINOL/Gold(III) Complexes: Synthesis and Catalysis with Tunable Product Profiles.

Unprecedented stable BINOL/gold(III) complexes, adopting a novel C,O-chelation mode, were synthesized by a modular approach through combination of 1,1'-binaphthalene-2,2'-diols (BINOLs) and cyclometalated gold(III) dichloride complexes [(C^N)AuCl2 ]. X-ray crystallographic analysis revealed that the bidentate BINOL ligands tautomerized and bonded to the AuIII atom through C,O-chelation to form a five-membered ring instead of the conventional O,O'-chelation giving a seven-membered ring. These gold(III) complexes catalyzed acetalization/cycloisomerization and carboalkoxylation of ortho-alkynylbenzaldehydes with trialkyl orthoformates.

Ruthenium(v) terminal arylimido corroles: isolation, spectroscopic characterization and reactivity.

Terminal Ru(v)-imido species are thought to be as reactive to group transfer reactions as their Ru(v)-oxo homologues, but are less studied. With the electron-rich corrole ligand, relatively stable and isolable Ru(v)-arylimido complexes [Ru(tBu-Cor)(NAr)] (H3(tBu-Cor) = 5,15-diphenyl-10-(p-tert-butylphenyl)corrole, Ar = 2,4,6-Me3C6H2 (Mes), 2,6-(iPr)2C6H3 (Dipp), 2,4,6-(iPr)3C6H2 (Tipp), and 3,5-(CF3)2C6H3 (BTF)) can be prepared from [Ru(tBu-Cor)]2 under strongly reducing conditions. This type of Ru(v)-monoarylimido corrole complex with S = ½ was characterized by high-resolution ESI mass spectrometry, X-band EPR, resonance Raman spectroscopy, magnetic susceptibility, and elemental analysis, together with computational studies. Under heating/light irradiation (xenon lamp) conditions, the complexes [Ru(tBu-Cor)(NAr)] (Ar = Mes, BTF) could undergo aziridination of styrenes and amination of benzylic C(sp3)-H bonds with up to 90% product yields.

The first crystallographically characterised ruthenium(vi) alkylimido porphyrin competent for aerobic epoxidation and hydrogen atom abstraction.

The syntheses of [RuVI(Por)(NAd)(O)] and [RuVI(2,6-F2-TPP)(NAd)2] have been described. [RuVI(2,6-F2-TPP)(NAd)(O)] capable of catalysing aerobic epoxidation of alkenes has been characterised by X-ray crystallography with Ru[double bond, length as m-dash]NAd and Ru[double bond, length as m-dash]O bond distances being 1.778(5) Å and 1.760(4) Å (∠O-Ru-NAd: 174.37(19)°), respectively. Its first reduction potential is 740 mV cathodically shifted from that of [RuVI(2,6-F2-TPP)(O)2].

Ruthenium porphyrin catalysed intermolecular amino-oxyarylation of alkenes to give primary amines via a ruthenium nitrido intermediate.

Ruthenium porphyrin catalysed direct intermolecular amino-oxyarylation of alkenes including styrenes and 1,3-dienes to give primary amines with O-(2,4-dinitrophenyl)hydroxylamine as the amine source was achieved in moderate to good yields under mild reaction conditions. Spectroscopic analyses revealed that a ruthenium nitrido complex was the key reaction intermediate for the amino-oxyarylation reaction.