Jean-Yves Godet

Action du péroxyde de di-t-butyle (PDTB) sur les alcoxyétains α-cyclopropaniques: étude de l'évolution de radicaux du type cyclopropylcarbinyle

Resume The oxidation of cyclopropyltin alkoxides with di-t-butyl peroxide yields cyclopropyl ketones and non-cyclic ketones. The results reported give new information concerning the behaviour of intermediate α-alkoxytin cyclopropylcarbyl free radicals.

Addition radicalaire de l’hydrure de tributylétain aux cétones α-cyclopropaniques et α-éthyléniques: mise en évidence d'un effet polaire

Abstract The reactivity with tributyltin hydride of two series of aromatic substituted α-cyclopropyl ketones, 2-phenylacetylcyclopropanes and benzoylcyclopropanes in the presence of a radical reaction initiator has been studied. In all cases it was observed that C 3 ring opening occurs and that electron-withdrawing substituents increase the rate of reaction. These results demonstrate the polar effect of the radical addition. The same results are obtained with aromatic substituted benzalacetones.

Reduction radicalaire de cetones α-cyclobutaniques par l'hydrure de tributyletain

Abstract The reaction of tributyltin hydride with cyclobutyl ketones results principally in reduction of the C=O group, but also rearrangement with opening of the ring structure occurs, depending on the nature of the alkyl group and the reaction conditions.

Direction of ring-opening of ring-substituted cyclopropyl(stannyloxy)methyl and cyclopropyl(hydroxy)methyl radicals: preferential formation of primary alkyl radicals

cis- and trans-2-Methylcyclopropyl-stannyloxymethyl and -hydroxymethyl radicals (A) have been generated by treating either the corresponding tin alkoxides or alcohols with t-butoxyl radicals, or the corresponding ketones with tributylstannyl radicals. The e.s.r. spectra show that, at low temperature (< –60°C), the cis-(A) radicals undergo ring-opening to give principally secondary alkyl radicals, but the trans-(A) radicals give only primary alkyl radicals.

Direction of ring-opening of 2-methyl-substituted cyclopropyl(stannyloxy)methyl and cyclopropyl(hydroxy)methyl radicals: kinetic and thermodynamic control

trans-2-Methylcyclopropyl(stannyloxy or hydroxy)methyl radicals undergo ring-opening to give principally the thermodynamically less stable primary alkyl radicals; use has been made of this effect to establish the conditions under which the cyclopropylmethyl → homo-allyl rearrangement is reversible.