A green approach for the synthesis of a set of ten 4-aryl substituted-5-alcoxy carbonyl-6-methyl-3,4-dihydro-2(1H)-pyridones using Meldrum’s acid has been devised, the absence of solvent and the activation with infrared irradiation in addition to a multicomponent protocol are the main reaction conditions. The transformations proceeded with moderated yields (50–75%) with a reasonable reaction rate (3 h). It is worth noting that two novel molecules of the new class of the bis-3,4-dihydropyridones were also obtained. In addition, a comparison without the use of infrared irradiation was performed.

Here we describe the efficient synthesis of alkyl 4-arylsubstituted-6-chloro-5-formyl-2-methyl-1,4-dihydropyridine-3-carboxylates and 4-arylsubstituted-4,7-dihydro-furo[3,4-b]pyridine-2,5(1H,3H)-diones via microwave-accelerated reaction of alkyl 4-arylsubstituted-2-methyl-6-oxo-1,4,5,6-tetrahydro-3-pyridinecarboxylates with the appropriate reagents. This eco-friendly approach to these valuable dihydropyridine derivatives does not involve the harsh or highly contaminating conditions common in classical heating and offers a reduction or even elimination of solvent use and recovery, simplification of the work-up procedures, facility of scale up, and low energy consumption, in addition to moderate to higher yields.

An efficient solid-phase approach to prepare substituted 1,4,5,6-tetrahydro-6-oxopyridines bearing a carboxylic acid group on C3 has been developed. The four-step protocol involves an initial acetoacetylation of polystyrene Wang resin, followed by preparation of resin-bound enamine. The cyclization reactions were carried out by reacting immobilized enamines with Knovenagel derivatives by a Hantzsch-type heterocyclization. Acidolytic cleavage from the solid support rendered the desired heterocyclic compounds in excellent yields and high purity. The synthesized compounds were structurally characterized by spectroscopic methods. In order to gain a better understanding of the structure of the obtained heterocycles, theoretical calculations at the ab initio (B3LYP/6-31G*) level were performed.