Jean Paul Paugam

Cyclopropane formation by electroreductive coupling of activated olefins and gem-polyhalo compounds

Abstract Cyclopropyl derivatives have been prepared with satisfactory yields by electroreductive coupling of activated olefins and gem -polyhalo compounds. The reaction is efficient when the olefin is more easily reduced than the organic halide. Two types of intermediates can be involved to lead to the products. The radical anion of the olefin can react with the halo compound by electron-tranfer followed by radical coupling, or be reduced into the dianion which reacts by nucleophilic displacement.

Copper-catalyzed electrosynthesis of 1-acyl-2,2-diphenylcyclopropanes and their behaviour in acidic medium

The formation of 1-acyl-2,2-diphenylcyclopropanes is performed under mild electrochemical conditions. These cyclopropane derivatives, through acid-catalyzed ring-opening, lead to γ,γ-diphenyl-β,γ-unsaturated carbonyl compounds which evolve into either substituted naphthalenes, or β-benzhydryl-α,β-cycloalkenones depending on the acyclic or cyclic nature of the intermediate allyl ketone.

Cyclopropane formation by nickel-catalysed electroreductive coupling of activated olefins and unactivated gem-dibromo compounds

Abstract Cyclopropyl derivatives have been prepared with good yields by transition-metal catalysed electroreductive coupling of activated olefins and unactivated gem-dibromo compounds. This electrolysis is characterized by the use of a Fe/Ni catalyst system, acetonitrile as the solvent and a catalytic amount of triphenylphosphine as ligand. This procedure is a good alternative to the classical preparations of cyclopropyl derivatives from activated olefins (Simmons–Smith reaction, 1,3-dipolar addition of diazomethane, 1,4-addition of phosphorus and sulfur ylides).

Electrochemical study of the formation of cyclopropanes from gem-dihalocompounds and alkenes catalyzed by copper 1,10-phenanthroline complexes

The reactions between four gem-dihalides 1, 2, 3, and 4 and styrene in the presence of copper-1,10-phenanthroline complexes were investigated. The formation of a cyclopropane derivative was only observed in the case of dimethyl dibromomalonate 1, while with the other gem-dihalides the addition products were formed by a radical chain addition mechanism. A study by cyclic voltammetry and chronoamperometry showed that the reduction of 1 by the copper(I) complex is a redox catalysis which is kinetically controlled by the rate of the concerted electron-transfer carbon-bromine bond-breaking. In the presence of styrene the formation of the cyclopropane proceeds by a radical addition followed by a concerted electron-transfer bond-breaking process.