Raymond Sauvêtre

Factors controlling the regioselectivity of additions to α-enones—VI: Reactions of acetonitrile and phenylacetonitrile anions

Abstract Reaction of α-enones 1a-g with acetonitrile anion 5 , in THF at −80° gives, irreversibly, alcohols 7 or 11 , resulting from carbonyl carbon attack, whatever the associated cation is (K + or Li + ). The reaction is considered to be under charge control. In THF, lithiated phenylacetonitrile 6 gives the alcohols 8 and 12 under kinetic control with benzalacetone 1b , 2-cyclohexenone 1d and 3-methyl 2-cyclohexenone 1e . Lithium alcoholate formation is reversible and ketones 10b, 14a and 14b formation, resulting from carbon 4 attack, is thermodynamically controlled. The other α-enones studied lead, under the same reaction conditions, to ketones 10a, 10c, 14c and 14d only. In a THF-HMPA mixture, reagent 6 only gives the starting α-enone, ketones 10 and 14 . The lower lying the α-enone LUMO level, the faster the reaction, which indicates, in the present case, that the transition state for carbon carbon double bond attack occurs relatively early in the reaction path.

Preparation et reactivite de fluorovinylzincs

Abstract Several fluorovinylzincs have been prepared. Palladium catalyzed cross coupling reactions give stereoselectively fluorinated compounds.

Synthese de difluoroalcenes-trans

Abstract Several trans-difluoro olefins have been prepared from chlorotrifluoroethylene via difluorovinylsilicon intermediates.

Préparation et réactivité de Et3SiCFCFM (M = Li, ZnBr)

Abstract Et 3 SiCFCFM (M = Li, ZnBr) has been prepared from CF 2 CFCl via 1,2-difluoro-1-triethylsilylethylene. Its reactions with electrophiles opens a way to trans -difluoro alkenes bearing various substituents.

Réactivité des diènes et styrènes fluorés obtenus par réaction de couplage au palladium

Abstract Fluorodienes and fluorostyrenes undergo clean cycloaddition to form perfluorocyclobutanes. Fluorostyrenes have been prepared by a palladium-catalyzed cross-coupling reaction. Treatment of fluorodienes under acidic conditions gives various α-fluorocarbonyl compounds.

Synthese stereospecifique de dienes fluores. II

Abstract Stereoselectively fluorinated conjugated dienes have been prepared by palladium catalysed cross coupling reactions.

Preparation et reactivite de quelques enynes fluores

Abstract Several fluoroenynes have been prepared by palladium—catalysed cross coupling reactions.

Synthese de difluoroolefines trans

Preparation de trans-difluoro-1,2 alcenes-1 a partir de (chloro trifluoro) ethylene via des (difluoro-1,2 alcene-1yl trimethyl) silanes

Synthèse et reactivité d'énynes fluorés☆

Abstract Several fluoroenynes have been prepared by palladium-catalyzed cross-coupling reactions. Cycloaddition reactions of these enynes give substituted cyclobutanes, whereas treatment with sulfuric acid leads to α-fluoro-α-allenic acid fluorides, lactones, α-fluoro-β-diketones or cyclic α-fluoroenones, according to the nature of the starting enyne. The cyclisation process is discussed.

Introduction stereoselective du groupement trifluoromethyle dans des systemes insatures

Abstract Treatment of 1,1-difluoro-1-alken-3-ols with diethylaminosulfur trifluoride (DAST) gives (E)-1,1,1-trifluoro-2-alkens with high regio and stereoselectivity.