International audienceThe development of environmentally benign reactions is an important goal in synthetic organic chemistry and chemical engineering. However, catalytic enantioselective oxidations using transition-metal complexes are limited when the oxidant is hydrogen peroxide. The two main difficulties of using hydrogen peroxide in the presence of transition metal complexes are the homolytic cleavage generating OH radicals and the catalase reaction with formation of dioxygen. The current applications of asymmetric sulfoxidation, epoxidation, dihydroxylation of alkenes and hydroxylation will be herein reported. Use of non-heme systems will be presented. The possibility of asymmetric oxidation catalyzed by metalloporphyrins will also be discussed

The asymmetric epoxidation of alkene and hydroxylation of arylalkane derivatives by H(2)O(2) to give optically active epoxides (enantiomeric excess (ee) up to 68%) and alcohols (ee up to 57%), respectively, were carried out in water/methanol solutions using chiral water-soluble manganese porphyrins as catalysts.

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International audienceA methodology is reported for the regioselective nitration of the phenyl groups of Halterman porphyrin, using NaNO2. These nitro-porphyrins can be reduced to aminoporphyrins and then N-dimethylated to give new optically active porphyrins. Applications to the asymmetric epoxidation of styrene derivatives by H2O2 to give optically active epoxides (ee up to 60%) and hydroxylation of alkanes to give optically active secondary alcohols (ee up to 69%) were carried out in organic solvents (dichloromethane/methanol) using chiral iron and manganese porphyrins as catalysts

a b s t r a c tThe metal complex FeTSPPCl (5,10,15,20-tetrakis)-(4-sulfonato-phenyl)-porphyrin-iron(III) chloride is an active catalyst for carbenoid insertion in N H bonds of aminoacid derivatives in aqueous media. A variety of diazoacetates and methyl diazophosphonate were used as carbenoid precursors. The commercially available iron porphyrin complex can also selectively catalyze alkylation of the N-terminus of insulin (chain B).

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International audienceDiscotic nickel dithiolene complexes are prepared by sulfuration of original benzil proligands appended with gallate fragments carrying long carbon chains (n = 8, 12, 16), separated from the dithiolene core by ester or amide linkers. The electronic properties of these functional nickel dithiolene complexes were studied by cyclic voltammetry and UV-vis spectroscopy. The thermotropic properties were investigated by a combination of POM observations, DSC analysis and X-ray diffraction experiments. The neutral dithiolene complexes, denoted CnesterNi and CnamideNi, all exhibit columnar phases over large temperature ranges including room temperature. CnesterNi complexes form columnar mesophases of rectangular (pseudo-hexagonal) and hexagonal symmetry whereas the amide linkage in CnamideNi complexes strongly stabilizes hexagonal columnar mesophases far below room temperature, as illustrated by C12amideNi which displays a Colh mesophase from −18 up to +177 °C. The role of hydrogen bonding between the amide functions in the stabilisation of the mesophases in CnamideNi complexes and their benzil precursors was confirmed by IR spectroscopy. Moreover, the C8amideNi compound exhibits a cubic phase, stable over [similar]50 °C, from 155 to 203 °C. Models for the arrangements within the different columnar mesophases are proposed and discussed

Symmetry plays a fundamental role in chiral recognition and enantioselective catalysis. Porphyrins possess a number of structural features that make them attractive for the stereocontrol of chiral recognition and metal-catalyzed asymmetric reactions. This article is a brief account of our studies on chiral recognition and enantioselective catalysis by optically active metalloporphyrins. Some of the studies on chiral recognition and asymmetric catalysis by metalloporphyrins performed by others have also been included when useful.