An efficient and green synthesis of novel highly functionalized nitrogen-fused pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidine derivatives using recyclable choline hydroxide

Choline hydroxide (ChOH) has been found to be a green and efficient basic ionic liquid catalyst for the synthesis of highly functionalized pyrido[2′,3′:3,4]pyrazolo[1,5- a ]pyrimidine derivatives through the reaction of a series of α,β -unsaturated ketones with 1 H -pyrazolo[3,4- b ]pyridin-3-amine under neat conditions. A series of α,β -unsaturated ketones with different substituted functional groups efficiently were converted to their corresponding products in good to excellent isolated yields, and the reactions can be easily scaled up to multigrams. The present environmentally benign and reusable ChOH catalyst offers several advantages such as shorter reaction times, a wide range of functional group tolerance and high yield of products via a simple experimental and work-up procedure. Graphical abstract The imparted features of this methodology are the green reaction, simple procedure, reusability, easy workability and high efficiency of ChOH.