Catalytic performance of cadmium pyrophosphate in the knoevenagel condensation and one-pot multi-component reaction of chromene derivatives

A simple, efficient, and eco-friendly process for the Knoevenagel condensation between various aromatic aldehydes and active methylene compounds and the synthesis of 2-amino-4H-chromene derivatives via a multi-component reaction of various aromatic aldehydes, malononitrile, and resorcinol catalyzed by mono-ammonium phosphate fertilizer (MAP) modified by cadmium chloride (CdCl₂) is described. This synthesis procedure is considered an attractive method due to its excellent yields, short reaction time, green conditions, cost-effectiveness, use of a non-toxic solvent, non-chromatographic purification of products, and recyclability of the catalyst.

Graphical abstract

A simple, efficient, and ecofriendly process is proposed to synthesize 2-amino-4H-chromene and 2-(4-chlorobenzylidene) malononitrile derivatives via the application of cadmium pyrophosphate (Cd₂P₂O₇) as catalyst prepared from the modification of mono-ammonium phosphate fertilizer (MAP) by adding cadmium chloride (CdCl₂). The products were obtained with good yields in a short reaction time.