Utilização de líquidos iônicos na síntese de enonas e de enaminonas

Abstract

The use of ionic liquids 1-butyl-3-methylimidazolium tetrafluorborate ([BMIM] [BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) as catalytic solvent in the synthesis of 1,1,1-trichloro(fluoro)-3-alken-2-onas [CX3C(O)C(R2)=C(R1)OR] from the reaction of enolethers or acetals with acyl halides is reported. The results obtained in the presence of ionic liquids were compared with those obtained in the conventional condition already developed in our laboratory, and they demonstrated great improvement in the reaction times, with maintenance of the good yields. Ionic liquids also were used in the reactions of enolethers with poor reactive acylants, as acetyl chloride and benzoyl chloride, proving its efficiency as catalytic media in this reaction type. The ionic liquids were still used as medium in the synthesis of β-enaminones bearing a trifluoro[chloro]methyl starting from the 1,1,1-trichloro(fluoro)-3-alken-2-ones. It was also evaluated the reutilization of the ionic liquids (recharge) after the reactions mentioned above. In all of the cases of recharge there was the maintenance of the times reacionais without significant loss of yield.