Single‐Step Photoinduced Radical Pentafluorosulfanylation and Cyclization of Alkenes for the Synthesis of SF 5 ‐Containing Cyclic Sulfinamides †

Comprehensive Summary The pentafluorosulfanyl (SF 5 ) moiety has garnered significant attention as a fluorinated functional group in the fields of medicinal chemistry, agrochemistry, and materials science, attributable to its distinctive physicochemical properties. In comparison to its structural analogue, trifluoromethyl, the SF 5 group demonstrates notably increased lipophilicity and pronounced electron‐withdrawing capacity. However, the direct pentafluorosulfanylation of unactivated alkenes remains challenging due to the intrinsic propensity of SF 5 Cl to undergo spontaneous chloropentafluorosulfanylation. Herein, we report a photoinduced radical pentafluorosulfanylation‐cyclization of alkenes enabled by an in situ substrate‐derived radical moderator strategy. Upon irradiation with LEDs, homolytic cleavage of the S–Cl bond in SF 5 Cl affords an electrophilic SF 5 radical, which undergoes addition to the alkene unit of the sulfinamide substrate, thereby generating a carbon‐centered radical intermediate. Subsequent intramolecular S H i cyclization yields the cyclic sulfinamide product, while a tert ‐butyl radical partakes in an XAT process with SF 5 Cl to regenerate the SF 5 radical and perpetuate the radical chain mechanism. Intriguingly, intramolecular hydrogen‐bonding interactions between the sulfinyl group and the CH 2 SF 5 moiety are posited to be responsible for the exceptional stereocontrol observed. Furthermore, the resulting SF 5 ‐containing motifs are readily amenable to further functionalization, thereby highlighting the broad synthetic utility and potential applications of these cyclic sulfinamides in pharmaceutical and materials science research.