A novel Deep Eutectic Solvent (MTPPBr/HGA-DES) was prepared by a mixture of methyl triphenylphosphonium bromide (MTPPBr) and hypogallic acid (HGA: 2,3-dihydroxybenzoic acid). The eutectic point phase diagram showed that the one mole of MTPPBr to two moles of HGA is the best mole ratio for the synthesis of a novel DES. Then, MTPPBr/HGA-DES was characterized by the FT-IR, TGA/DTA, densitometer, eutectic points, and 1H NMR techniques, and used as a novel catalyst for the green synthesis of new pyrano[2,3-d]pyrimidines 2(a-j) via a one-pot four-component condensation reaction of 4-hydroxycoumarin, barbituric acid, morpholine and benzaldehydes at 80 C in solvent-free conditions.
