Metal-Free Photoinduced Hydrogen Atom Transfer for Direct Thiolation of Hydridic α-C(sp3)–H of Ethers

C–S bond formation via hydrogen atom transfer (HAT) remains underdeveloped despite the importance of thioethers in organic synthesis, materials science, and medicinal chemistry. Herein, we report a mild, rapid, and operationally simple method for the direct α-C(sp3)–S bond formation in ethers using alkyl or aryl thiosulfonates as sulfur sources and (4-methoxyphenyl)(4-(trifluoromethyl)phenyl)methanone as the diaryl ketone catalyst. The reaction proceeds at room temperature under a 390 nm irradiation, delivering a broad range of thioethers in the absence of metals or stoichiometric oxidants. The method exhibits excellent functional group tolerance, predictable regioselectivity favoring the most hydridic C–H bonds, and compatibility with various cyclic and acyclic ethers and amides. Preliminary mechanistic studies support a radical pathway consistent with a well-established photoexcited ketone-mediated HAT followed by radical addition to the thiosulfonate. This approach expands the toolkit for redox-neutral C(sp3)–S bond construction.