Polyethylene glycol-bonded 1,8-diazabicyclo[5.4.0]undec-7-ene (PEG–DBU) as a surfactant-combined base catalyst for the application of nucleosides as reagents in multi-component syntheses of 8-substituted pyrido[2,3-d]pyrimidine-6-carbonitriles in water

Polyethylene glycol-bonded 1,8-diazabicyclo[5.4.0]undec-7-ene (PEG-DBU) was prepared as a new surfactant-combined base catalyst and successfully applied in the syntheses of some novel 8-substituted pyrido[2,3-d]pyrimidine-6-carbonitriles viaone-pot multi-component reactions in water using nucleosides (adenosine, guanosine and cytidine) as starting materials. The application of PEG-DBU used water as an available, green, and benign reaction medium instead of commonly used hazardous solvents (DMF, DMSO etc.) for the manipulation of nucleosides.