An efficient synthesis of functionalized 3-(α-amidobenzyl)-4-hydroxycoumarin derivatives by NanoSiO2-BF3 promoted condensation reaction between aromatic aldehyde, 4-hydroxycoumarin, and amides

Recently, multi-component and domino reactions are efficient and effective methods in the sustainable synthesis of heterocycles. Due to atom economy and simplicity of One-Pot procedures, multi-component reactions occupy a superior position compared with other reactions. These reactions are widely applied in pharmaceutical chemistry for producing different structures and combinatorial libraries for drug discovery [1-2]. Coumarin and chromene and their derivatives have attracted considerable attention from organic and medicinal chemists for many years as a large number of natural products contain this heterocyclic nucleus. They are widely used as additives in food, perfumes, cosmetics, pharmaceuticals and optical brighteners and dispersed fluorescent and laser dyes. Thus the synthesis of derivatives of this nucleus is of much interest [3]. Herein we have researched three-component coupling of 4-hydroxycoumarin 1, aryl aldehydes 2, and amides 3, in the presence of NanoSiO2-BF3 as heterogeneous catalyst to the synthesis of 3-(α-amidobenzyl)-4-hydroxycoumarin derivatives 4.