Facile Construction of Novel Fused Chromeno[2,3-d]Thiazolo[3,2-a]Pyrimidine Derivatives in Biocompatible Ionic Liquid under Solvent-Free Conditions

A simple and efficient three-component reaction is reported between 2,3-dihydro-7-hydroxythiazolo[3,2-a]pyrimidin-5-one, dimedone and aromatic aldehydes for synthesis of biologically important novel heterocycles containing thiazolo[3,2-a]pyrimidine and chromene as biologically active moieties. The SO3H-functionalised halogen-free ionic liquid [MIM(CH2)4SO3H][HSO4-] is found to be an environmentally benign catalyst for this reaction without using any solvent. This SO3H-functionalised ionic liquid could be recovered and used at least four times without considerable reduction in activity. Good functional group tolerance, broad scope of usable substrates and good to excellent yields of products are the other prominent features of the present synthetic protocol.