I2‐Catalyzed Chemodivergent Synthesis of Dihydrofuro[3,2‐c]coumarins and Pyrano[3,2‐c]coumarins

Abstract

We have developed a chemodivergent protocol for synthesizing furo[3,2‐c]coumarins and pyrano[3,2‐c]coumarins from easily accessible reagents through oxidative cyclization and condensation reaction, respectively. A library of dihydrofuro[3,2‐c]coumarins and pyrano[3,2‐c]coumarins has been synthesized by just tuning the reaction conditions. Moreover, furo[3,2‐c]coumarin could be synthesized through a one‐pot two‐step approach. High chemoselectivity was observed in the case of formation of dihydrofuro[3,2‐c]coumarins. Mild and metal‐free reaction conditions, operational simplicity, use of inexpensive catalyst, broad functional group tolerance, and practicability are the important facets of this strategy. Detailed mechanistic investigation indicated the radical pathway for oxidative cyclization. Whereas, theoretical studies showed that the greater electrophilicity of the carbonyl group in acetonitrile is responsible for the preferential formation of pyrano[3,2‐c]chromen‐5‐ones.