Ionic Liquid Catalyzed 4,6-Disubstituted-3-Cyano-2-Pyridone Synthesis Under Solvent-Free Conditions

A green protocol for the synthesis of 4,6-disubstituted-3-cyano-2-pyridones from cyanoacetamides and 1,3-dicarbonyl compounds or chalcones using guanidine based ionic liquid as catalyst has been developed. In solvent-free conditions at 30 °C, [TMG][Lac] (1,1,3,3-tetramethylguanidine lactate) was found to have the highest catalytic activity among the ionic liquids including [TMG][Ac] (1,1,3,3-tetramethylguanidine acetate), [TMG][Pr] (1,1,3,3-tetramethylguanidine propionate), [TMG][n-Bu] (1,1,3,3-tetramethylguanidine n-butyrate) and [TMG][TFA] (1,1,3,3-tetramethylguanidine trifluoroacetate). The catalyst was recovered and recycled several times without significant loss of catalytic activity.