ELECTROCHEMICAL TRIFLUOROMETHYLATION OF 3-SULPHOLENE - SYNTHESIS OF MESO-3,4-BIS(TRIFLUOROMETHYL)SULPHOLANES AND DL-3,4-BIS(TRIFLUOROMETHYL)SULPHOLANES

Electrochemical trifluoromethylation of 3-sulpholene (1) in a CF3COOH/ CH3COONa/CH3CN/H2O system gives a complex mixture consisting of meso- and DL-3,4-bis(trifluoromethyl)sulpholanes (2a) and (2b) as the major components and isomeric trifluoromethylsulpholenes 3a and 3b, 3,4-bis( trifluoromethyl) sulpholenes 4a and 4b, 3-trifluoromethylsulpholane 5 and 2,3,4-tris( trifluoromethyl) sulpholanes 6a-c as the minor compon ents with a 40-50% total yield. Compounds 2a and 2b were efficiently i solated from the crude reaction mixture and fully identified by spectr al methods. The reaction conducted in a CF3COOH/CF3COONa/H2O system, w ithout acetonitrile, gave 4-trifluoromethyl-2-sulpholene (3a) as the m ain product, albeit total yield was low. (C) 1998 Elsevier Science S.A .