Synthesis of novel coumarinyl-pyrido[2,3-d]pyrimidine-2,4-diones using task-specific magnetic ionic liquid, [AcMIm]FeCl₄ as catalyst

An acid-functionalized magnetic ionic liquid, 1-acyl-3-methylimidazolium tetrachloroferrate, [AcMIm]-FeCl4 has been utilized for the synthesis of a series of novel highly functionalized coumarinyl-pyrido[2,3-d]pyrimidine-2,4-dione derivatives (3a-3l) by the reactions of various 3-chloro-3-(2-oxo-2H-chromen-3-yl)acrylaldehydes (1) with functionalized aryl, 6-aminouracils. The major significant of the present procedure is the use of task-specific acidic ionic liquid which act as catalyst as well as reaction medium and thus avoiding use of organic solvent and/or protic acid catalyst. The other major advantages of the protocol are (i) shorter reaction time (1 h), (ii) easy work up procedure, (iii) excellent yields of products (91-94%), and (iv) recyclability of catalyst. The compounds (3a-3l) were identified using FT-IR, 1H NMR, and 13C NMR and mass spectroscopic studies.