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

• Published in: Journal of the Chinese Chemical Society (Taipei) 2020-10, Vol.67 (10), p.1895-1902
• Main Authors: Ebrahimi, Mitra, Abdolmohammadi, Shahrzad, Kia‐Kojoori, Reza
• Format: Article
• Language: English
• Subjects: [1,3]dioxolo[g]chromeneones; aqueous media; environmentally benign procedure; pyrano[c]chromenediones; recyclability of catalyst; silver(I) dichromate (Ag2Cr2O7 NPs)
• ISSN: 0009-4536; 2192-6549
• DOI: 10.1002/jccs.201900488

An 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. In this study, 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 were synthesized in high yields via the cyclocondensation reaction of active methylene compounds including 4‐hydroxycoumarin or 3,4‐methylenedioxyphenol, aromatic aldehydes, and meldrum's acid in the presence of a catalytic amount of Ag2Cr2O7 Nanoparticles in water at ambient temperature. 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.