An efficient synthesis of pyranopyrimidine derivatives by using glyoxylic acid:L-proline deep eutectic solvent as a novel designer reaction promoter

Abstract

As part of green chemistry, we have designed a novel deep eutectic solvent (DES) by using glyoxylic acid: L-proline (1:1) and efficiency of novel DES has been studied for the synthesis of pyrimidine core derivatives via multicomponent reaction. It is an efficient solvent/catalyst to develop a series of 7-amino-2,4-dioxo-5-aryl-1,3,4,5-tetrahydro-2H-pyrano[2,3- d]pyrimidine-6-carbonitrile derivatives. The pyranopyrimidine derivatives have been synthesized through a one-pot three component reaction of barbutric acid/thiobarbutric acid, aryl aldehydes and malononitrile through Knoevenagel condensation followed by Michael addition and subsequent cyclization. The thermogravimetric analysis and differential scanning calorimetry have been used to identify thermal stability and working temperature range of novel DES. The reusability of the glyoxylic acid:L-proline (1:1) has been tested and the results revealed that the recovered catalyst can be reused at least four additional times in subsequent reactions without significant decrease in product yield. The use of solvent glyoxylic acid: L-proline (1:1) DES to yield vital pyrimidine molecules provide this protocol to cope with the current need for efficient, cost-effective, cleaner reaction profiles, effortless work phase with high yield of product, and with short reaction time and eco-friendly methodology. IR, 1H NMR and MS and alternative methods, whenever available, have verified the chemical structures of the targeted compounds.