Procedure for the preparation of racemic and enantionmerically pure derivatives of 1,5-diaryl-3-trifluoromethyl-Δ2-pyrazolines

Abstract

Procedure for preparation of compounds with the general formula 1, which include the racemic mixtures (±)-1, and the enantiomeric ally pure compounds (−)-1 and (+)-1, wherein Rand R, like or different, represent an atom of hydrogen, chlorine, fluorine, a methyl, trifluoromethyl or methoxy group; Rrepresents an atom of hydrogen, chlorine, fluorine, a methyl, trifluoromethyl, methoxy, trifluoromethoxy, methylsulphonyl or aminosulphonyl group; Rrepresents an atom of hydrogen, chlorine, fluorine, a methyl, trifluoromethyl, methoxy, trifluoromethoxy, methylsulphonyl or aminosulphonyl group, with the condition that one of the substituents Ror Ris a methylsulphonyl or aminosulphonyl group; which involves obtaining the racemic mixture with the general formula (±)-1 by reacting an (E)-1,1,1-trifluoro-4-aryl-3-buten-2-one with a phenylhydrazine, followed by a treatment with chlorosulphonic acid, or by reacting with chlorosulphonic acid followed by a reaction with sodium hydroxide and, finally, with thionyl chloride. The product obtained by either of these methods is made to react with ammonium carbonate or ammonia, or with sodium sulphite and methyl iodide or methyl sulphate. In addition, to obtain the enantiomerically pure compounds with the general formula 1 by resolving the racemic mixture with the general formula (±)-1, a reaction is effected with optically active ephedrine, followed by formation of the sodium salt of each enantiomer, reaction with thionyl chloride and ammonium carbonate or ammonia, or instead with thionyl chloride followed by sodium sulphite and methyl iodide or methyl sulphate to thereby obtain separately the enantiomerically pure compounds with the general formulae (−)-1 and (+)-1.