M. Vincens

Synthese de nouveaux sels de tetraphosphonium macrocycliques

Resume A one step synthesis of tetraphosphonium salts of the saturated 5 and ethylenic 3 macrocycles containing CC bridges has been carried out in good yield. The cleavage of the carbon bridges during basic hydrolysis is highly regioselective.

Synthese de nouveaux oxydes de tetraphosphines macrocycliques

Abstract The direct cycloadditions of two dioxophosphidure dianons with two molecules of an unsaturated dihalide produce unsaturated macrocyclic phosphine tetraoxides that are alkylated on phosphorus. Their reduction by molecular hydrogen is highly selective: the saturated homologues are obtained in excellent yield.

Transposition sigmatropique de cetones α-cyclopropeniques en milieu acide

Abstract In protic media 1-acyl 2-cyclopropene derivatives undergo a highly selective ring expansion reaction leading to cyclobutenes. This homoallylic 1-(2-cyclopropenyl) 1-hydroxy- ethylium cation rearrangement is an excellent approach to difunctional cyclobutene derivatives.

Le radical (cyclopropene-1 yl)-1 alkyle. Stereoselectivite de la substitution radicalaire allylique en serie cyclopropenique

Abstract The halogenation of ethyl 1,2-dialkyl cyclopropanecarboxylate by t-butyl hypochlorite occurs spontaneously in the dark. The conjugated radical is well depicted by the methylene-cyclopropane structure.

Complexation of alkali metal and tetramethylammonium ions with polyacids. pH-Metry consequences

Mass Spectrometry (MS) enables the study of alkali metal and tetramethylammonium (TMA) complexes which are formed during potentiometric titrations. Their formation and their evolution as a function of pH are confirmed by means of 23Na NMR spectroscopy. This is a common phenomenon which calls the principle of pH-metric titration of polyacids into question.

Trioxaphosphocanes-1,3,6,2, etude par R.M.N. (13C, 1H, 31P et stereochimie

Abstract The stereochemistry of several 2-R-1,3,6,2-trioxaphosphocanes (R = Cl, OCH3, CH3, N(CH3)3 has been investigated by 1H, 13C and 31P n m r spectroscopy.