N^1,N^1,N^2,N^2-tetramethyl-N^1,N^2-bis(sulfo)ethane-1,2-diaminium trifluoroacetate as an efficacious and dual-functional catalyst for the solvent-free preparation of pyrido[2,3-d:6,5-d′]dipyrimidines

Ionic liquid N^1,N^1,N^2,N2tetramethylN^1,N2bis(sulfo)ethane1,2diaminium trifluoroacetate ([TMBSED][TFA]2) was utilized as an efficacious and dualfunctional catalyst for the onepot multicomponent reaction of arylaldehydes, 2thiobarbituric acid and ammonium acetate under the solventfree conditions to afford pyrido[2,3d:6,5d′]dipyrimidine derivatives. Dualfunctionality of [TMBSED][TFA]2 (having acidic and basic groups) caused that the products were obtained in high yields and short reaction times. Moreover, a logical mechanism based on dualfunctionality of the catalyst was proposed.