Ag2Cr2O7 nanoparticles: An eco‐friendly and reusable catalyst for synthesis of pyrano[c]chromenediones and [1,3]dioxolo[g]chromeneones in aqueous media at ambient temperature

Abstract

AbstractAn efficient and green protocol for the synthesis of 4‐aryl‐3,4‐dihydro‐2H,5H‐pyrano[3,2‐c]chromene‐2,5‐diones and 8‐aryl‐7,8‐dihydro‐6H‐[1,3]dioxolo[4,5‐g]chromene‐6‐ones through the Ag2Cr2O7 nanoparticles catalyzed cyclocondensation reaction of active methylene compounds including 4‐hydroxycoumarin or 3,4‐methylenedioxyphenol, aromatic aldehydes, and meldrum's acid in water at ambient temperature was described. This method demonstrates several advantages compared with methods that are currently employed such as a mild reaction conditions, simple work‐up, good to excellent yields, avoiding toxic catalyst and hazardous solvent, and recovery and reuse of the catalyst.