N1,N1,N2,N2-tetramethyl-N1,N2-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 N1,N1,N2,N2-tetramethyl-N1,N2-bis(sulfo)ethane-1,2-diaminium trifluoroacetate ([TMBSED][TFA]2) was utilized as an efficacious and dual-functional catalyst for the one-pot multi-component reaction of arylaldehydes, 2-thiobarbituric acid and ammonium acetate under the solvent-free conditions to afford pyrido[2,3-d:6,5-d′]dipyrimidine derivatives. Dual-functionality 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 dual-functionality of the catalyst was proposed.