Deep eutectic solvent-assisted fast and green synthesis of benzochromenopyrimidines and pyranopyrimidines

A novel Deep Eutectic Solvent (MTPPBr/GA-DES) was prepared by a mixture of methyl triphenylphosphonium bromide (MTPPBr) and gentisic acid (GA: 2,5-dihydroxybenzoic acid). The eutectic point phase diagram showed that one mole of MTPPBr to one mole of GA is the best mole ratio for the synthesis of the new DES. Then, it was characterized by the FT-IR, NMR, densitometer, and TGA/DTA techniques and used as a capable and novel catalyst for the very fast and green synthesis of: i) Five new 2(a-e) and five known benzo[6,7]chromeno[2,3- d ]-pyrimidines 2(f-j) and ii) Fourteen known pyrano[2,3- d ]-pyrimidines 3(a-l) , in solvent-free conditions, short reaction times and high yields.