1,2-Dimethyl-N-butanesulfonic acid imidazolium hydrogen sulfate as efficient ionic liquid catalyst in the synthesis of indeno fused pyrido[2,3-d]pyrimidines Synthesis of indeno fused pyrido[2,3-d]pyrimidines

Indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidin-4,6-(5h,11h)dione derivatives were synthesized regioselectively in high yields by a three-component reaction of 1,3-indanedione,aromatic aldehydes and 2,6-diaminopyrimidin-4(3h)-one in the presence of 1,2-dimethyl-n-butanesulfonic acid imidazolium hydrogen sulfate ([dmbsi]hso4) ionic liquid as green and reusable catalyst. this protocol produced the desired products in high yields (87–95%) and short reaction times (3–6 min). © 2014 the authors