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

A metal-free approach for C(sp(3))-H activation followed by an intramolecular Giese reaction to construct a wide range of cyclic ether scaffolds of various ring sizes under environmentally benign and straightforward conditions is reported. An easily prepared pyrylium salt is employed as an organophotocatalyst for this visible-light-driven, highly atom-economical (PMI = 64.34 gig for a 0.2 mmol scale), cost-effective, and chemoselective transformation. The reported method has a broad functional-group tolerance, resulting in good-quality products. Furthermore, downstream functionalizations of a product and a gram-scale synthesis (PMI = 17.41 g/g for a 10 mmol scale) are demonstrated, highlighting our method's advantages.