Jean-François Bartoli

Manganese porphyrins covalently bound to silica and montmorillonite K10 as efficient catalysts for alkene and alkane oxidation by hydrogen peroxide

Abstract New supported Mn III -porphyrin-based catalysts were prepared by covalent binding of meso -tetrakis-(2,6-dichlorophenyl) porphyrin derivatives bearing NH 2 or SO 3 H functions on their meso -aryl rings to either silica or montmorillonite K10. All these supported metalloporphyrins efficiently catalysed the epoxidation of alkenes with PhIO. The Mn III -porphyrin covalently bound to montmorillonite K10 gave remarkably good results for the hydroxylation of linear alkanes such as heptane with PhIO, the obtained yields (54%) being much better than those observed with corresponding homogeneous catalysts. The Mn III -porphyrin covalently bound to silica was an efficient catalyst for epoxidation of alkenes with H 2 O 2 (yields between 65 and 95% under conversion conditions). In the presence of an excess of substrate, this supported catalyst was found to be able to catalyse alkene epoxidation with yields based on H 2 O 2 between 67% and 88%, as well as alkane hydroxylation with yields between 21% (for heptane) and 90% (for cyclooctane).

Mono-oxigenase-like dioxygen activation leading to alkane hydroxylation and olefin epoxidation by an MnIII(porphyrin)–ascorbate biphasic system

A biphasic H2O–C6H6 system, which has MnIII(tetraphenylporphyrin)(Cl) and a phase transfer agent as catalysts and ascorbate as a reducing agent, activates dioxygen leading to selective epoxidation of olefins and hydroxylation of alkanes under mild conditions.

A new manganese-β-heptanitro-porphyrin with extreme redox potentials: spectral, electrochemical and catalytic properties

Abstract Manganese tetra-(2,6-dichlorophenyl)-β-heptanitroporphyrin was prepared by selective heptanitration of Zn(TDCPP=tetra-(2,6-dichlorophenyl)porphyrin), demetallation of the resulting porphyrin and treatment with Mn(OAc)2. It exists as a high-spin Mn(II) complex and it is electrochemically oxidized to the corresponding Mn(III) complex which exhibits the highest redox potential reported so far for an Mn(III) porphyrin (+940mV versus SCE). Moreover it acts as a three-electron reservoir after three successive, reversible reductions at potentials unusually high for such reactions (+43, −220 and −745 mV versus SCE). It is also a good catalyst for alkene epoxidation and alkane hydroxylation by PhIO which constitutes a non-classical behavior for an Mn(II) porphyrin.

Hydroxylation of linear alkanes catalysed by iron porphyrins: particular efficacy and regioselectivity of perhalogenated porphyrins

Iron porphyrins containing perhalogenated pyrroles are found to be much better catalysts for the hydroxylation of poorly reactive alkanes like pentane or heptane by PhIO (yields as high as 80%) than the corresponding iron porphyrins without halogens on the pyrrole rings; the chemoselectivity and regioselectivity of the oxidations are found to vary very much with the presence of pyrrole halogens suggesting a dramatic change in the structure of the oxygenating iron-oxo species.

An easy access to polyhalogenated metalloporphyrins covalently bound to polymeric supports as efficient catalysts for hydrocarbon oxidation

Reaction of silica, montmorillonite and polystyrene bearing amino functions with several polyhalogenated metalloporphyrins gave an easy one-step access to new supported catalysts, owing to a selective nucleophilic substitution of the para-halogen atoms of the porphyrin meso-aryl groups by the polymer amine function; these catalysts were very active for cyclooctene epoxidation and alkane hydroxylation by PhlO.

Iron polynitroporphyrins bearing up to eight β-nitro groups as interesting new catalysts for H2O2-dependent hydrocarbon oxidation: unusual regioselectivity in hydroxylation of alkoxybenzenes

A series of iron porphyrins bearing one to eight beta-nitro substituents were synthesized and evalauted as catalysts for hydrocarbon oxidation with H2O2; iron porphyrins bearing five or six beta-nitro groups were the best catalysts for cyclooctene epoxidation and adamantane or anisole hydroxylation without need of a cocatalyst, and led to very different regioselectivities with either H2O2 or PhIO as oxidants, as shown by an unusual ortho-hydroxylation of alkoxybenzenes highly favored in the H2O2-dependent oxidations.

New manganese β-polynitroporphyrins as particularly efficient catalysts for biomimetic hydroxylation of aromatic compounds with H2O2

A series of Mn porphyrins bearing one to eight β-nitro substituents were synthesized in high yield in three steps by using a new general method for selective nitration of a Zn(meso-tetraarylporphyrin); this Mn porphyrin series exhibits a remarkably wide span of Mn(III)/Mn(II) redox potentials from −290 to + 1150 mV (vs. SCE), and the Mn porphyrins bearing one to five β-nitro groups are particularly good catalysts for hydroxylation of aromatic compounds with H2O2, with yields up to 98, 83, 80 and 12%, respectively for anisole, naphthalene, acetanilide and ethylbenzene.