DABCO-based ionic liquids: introduction of two metal-free catalysts for one-pot synthesis of 1,2,4-triazolo[4,3-a]pyrimidines and pyrido[2,3-d]pyrimidines

Abstract

Straightforward methods for the synthesis of 1,2,4-triazolo[4,3-a]pyrimidine and pyrido[2,3-d]pyrimidine derivatives are described through three-component condensation of aromatic aldehydes, malononitrile, and 3-amino-1,2,4-triazole or 6-amino-1,3-dimethyluracil. In both procedures two affordable and metal-free DABCO-based ionic liquids are employed as catalysts and the obtained outcomes are compared with each other. All reactions are performed under mild conditions during acceptable reaction times in good to high yields. After ensuring the efficiency of the catalysts in both reactions, four new derivatives are synthesized and their structures are characterized by FT-IR, ¹H NMR and ¹³C NMR. Simplicity, easy work-up procedures and recoverability of the catalysts are other advantages of these methods.