Improved microwave-assisted catalyst-free synthesis of 9-aryl-5,9-dihydropyrimido[4,5-d][1,2,4]triazolo[1,5-a]pyrimidine-6,8(4H,7H)-dione derivatives

A green regioselective synthesis of some new and known 9-aryl-5,9-dihydropyrimido4,5-d]1,2,4]triazolo1,5-a]pyrimidine-6,8(4H,7H)-diones has been described via the microwave-assisted one-pot reaction of 3-amino-1H-1,2,4-triazoles, aromatic aldehydes and barbituric acids under solvent- and catalyst-free conditions. This operationally simple procedure is less laborious and provides a better scope than previously reported procedures.