Thiochromane Formation via Visible-Light-Mediated Intramolecular δ-C(sp 3 )-H Bond Arylation of Sulfonamides.

Visible-light-mediated intramolecular site-selective δ-C(sp 3 )-H bond arylation of aliphatic trifluoromethanesulfonamides was developed. The reaction proceeds through a radical cascade, including the generation of a sulfonamidyl radical, which triggers a 1,5-hydrogen atom transfer, affording a δ-C-centered radical, which finally cyclized onto a neighboring thiopolyfluoroaryl moiety to deliver a range of synthetically useful thiochromanes. The cyclization process occurs through two distinct pathways depending upon the nature of the substituent X ortho to the native C-S bond.