Synthesis of Indeno[1,2-c]furans via Cobalt-Catalyzed Radical-Polar Crossover [3 + 2] Cycloaddition of o-Alkynylaryl β-Dicarbonyls.

Fused polycyclic furans are privileged structural scaffolds in materials chemistry, including organic semiconductors. Specifically, indeno[1,2-c]furans are an interesting type of polycyclic furans featuring a fused furan and indenone framework. Unfortunately, limited studies on their photophysical properties have been performed, probably owing to the lack of efficient and straightforward approaches to those compounds. Herein, we have developed a cobalt-catalyzed radical-polar crossover cyclization of the readily available o-alkynylaryl β-carbonyls to afford diverse indeno[1,2-c]furans. Photophysical and DFT calculations were also carried out, suggesting that the obtained indeno[1,2-c]furans exhibit promising electronic and optical properties.