A. Bensadat

Anodic functionalization of vinyl sulfides. Formal access to gem or vicinal aryl thioether dications

Abstract The anodic oxidation of a number of vinyl thioethers has been performed in CH 3 CN-Et 3 N,3HF. Results clearly show that the reactivity of the vinyl sulfide radical cation depends on several factors as structure of substrates and nucleophilic conditions. For example a dimerization occurred from the unsubstituted vinyl sulfide 1a (CH 2 =CH-SPh) whereas α,β- and/or β,β-difluoro sulfides were obtained from substituted homologues. In order to understand this reactivity the anodic behaviour of 1a and 1b (Ph-CH=CH-SPh) has been especially analysed in two other nucleophilic media (CH 3 OH/Et 3 N,3HF and AcOH/AcOK) leading respectively to methoxylation and acetoxylation of starting compounds. Comparison with electrofluorination results has allowed us to propose a mechanism involving an intermediary episulfonium ion which could explain the formation and ratio of the products isolated.

Fluoration anodique dans le chlorure de methylene (polymethyl- et vinylbenzenes)

Abstract The anodic oxidation of polymethyl and of ethylenic derivatives of benzene in CH 2 Cl 2 /Et 4 NF, 3HF or Et 3 N, 3HF has been studied. The fluoro compounds are obtained in good yields. With the ethylenic compounds cis-addition products predominate.

A new synthesis of enaminoketones

Abstract A new and efficient synthesis of enaminoketones is described. E,Z β-chloroacroleine derivatives react with secondary amines to produce enaminoketones. The reaction was essentially studied with β-trifluoromethylacroleines.

Regioselective synthesis of (trifluoromethyl)-β-chloroenones

Abstract The regioselectivity of the conversion of 1,3-diketones into β-chloroenones can be changed by the appropriate choice of the reagent:reaction with “Vilsmeiers reagent” prepared from POCl3, and dimethylformamide or treatment of the diketone with the oxalyl chloride in the presence of dimethylformamide.

Electrosynthesis of fluoroorganic compounds

Abstract When polymethylbenzenes are electrochemically oxidized in CH 3 CNEt 4 NF, 3HF or CH 3 CN-pyridine, 10HF side chain monofluorination takes place. Polyalkylbenzylacetamides are formed as by-products. The first electron transfer gives a radical-cation. The radical-cation having a high positive density on a substituted position are converted to benzyl radicals by loss of a proton and the benzyl radicals are rapidly oxidized to benzyl cations. The reactivity order of anodically generated cations toward fluoride ions and acetonitrile appears to be classical; the more stable cations are more selective toward fluoride ions. In order, to obtain only benzyl fluoride, methyl chloride can be used as solvent. Ethylenic compounds may also provide cation radicals by electro chemical oxidation and fluoroamidation or difluoration takes place The halofonctionnalisation of 8 phenyl substituted olefines will be discussed (A/B ratio, stereochemistry,…).