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

Abstract

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 solventfree 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.

Protic Ionic Liquids: Evolving Structure–Property Relationships and Expanding Applications

“…521 Specifically, the PILs trialed consisted of the TMG cation paired with lactate, acetate, propionate, n-butyrate, or trifluoroacetate (TFA). Of these PILs, the TMG lactate led to the best yield, and was recycled and reused four times with no loss of activity.…”

“…The high yield in TMG lactate was attributed to this PIL being the most basic and having a low viscosity. 521 The heterocyclic 6-aminouracils were formed from cyanoacetylureas using TMG lactate for the ring closure. 522 Yields were obtained between 84% and 92%, with the IL able to be recovered and reused at least five times with little loss of yield.…”

Mesostructured SBA-15-Pr-SO3H: An efficient solid acid catalyst for one-pot and solvent-free synthesis of 3,4-dihydro-2-pyridone derivatives

“…Although several approaches for the synthesis of these skeletons have been reported, [24][25][26][27][28] (table 2). After completion of the reaction (monitored by Thin layer chromatography (TLC)), the crude product was dissolved in hot ethanol and separation of the heterogeneous solid catalyst from the reaction medium was easily carried out by simple filtration.…”

Ionic Liquids-Prompted Synthesis of Biologically Relevant Five- and Six-Membered Heterocyclic Skeletons

“…Chavan and Degani [198] reported a green protocol for the synthesis of 4,6-disubstituted-3-cyano-2-pyridones 107 & 108 from cyanoacetamides and 1,3-dicarbonyl compounds or chalcones using IL under solvent-free conditions SCHEME was correlated with its more basic nature due to reduction in acidity because of intramolecular hydrogen bonding in lactic acid. The catalyst was recovered and reused for several times without appreciable loss in product yield.…”