Synthesis of Unsymmetrical 1, 4-Dihydropyridine Derivatives in Ionic Liquid and Inference on the Formation Mechanism of Furopyridines

Abstract

Aromatic aldehydes, methyl acetoacetate, ethyl acetoacetate, ammonium acetate, ethyl 4-chloroacetoacetate as materials, eight unsymmetrical 1, 4-dihydropyridine derivatives were synthesized in ionic liquid [Bmim]OH in short time with the 60%-90% yield, and the ionic liquid could be utilized for 5 times repeatedly with the no decrease of the yield, four of products [3(a-d)] (see in Table-1) were synthesized through Knoevenagel and Michael addition reaction, and another four Furopyridines [3(e-h)] (see in Table-2) through one-pot synthesis whose formation mechanism being different from that of [3(a-d)] was first inferred.