Visible-Light-Mediated Organophotocatalyzed C(sp3)–H Activation and Intramolecular Cyclization

Abstract

A metal-free approach for C(sp 3)–H activation followed by intramolecular Giese reaction to construct a wide range of cyclic-ether scaffolds of different ring sizes is reported using environmentally benign and straightforward conditions. An easy-to-prepare pyrylium salt is employed as an organo-photocatalyst for this visible-light-driven, high atom-economical (PMI = 64.34 g/g for 0.2 mmol scale), cost-effective and chemoselective transformation. The reported methodology has high functional group tolerance, resulting in good-quality products. Further, downstream functionalization of the products and a gram scale synthesis (PMI = 17.41 g/g for 10 mmol scale) is demonstrated, highlighting our methodology's advancement.

Photo/Electrochemical‐Mediated C(sp3)−H Bond Functionalization of (Thio)Ethers

“…In 2022, Sureshkumar's group developed a method for photocatalytic chain ether C(sp 3 )−H functionalization/cyclization for the synthesis of cyclic ethers (Scheme 8a) [16] . This strategy offers the advantages of greenness, atomic economy, efficient chemoselectivity, and good functional group tolerance.…”