Light-Promoted Cobalt-Catalyzed Radical Markovnikov Hydrothiolation of Alkenes with N-Arylsulfenyl Phthalimides

In recent years, transition-metal hydride catalysis has emerged as a powerful strategy for radical Markovnikov hydrothiolation of alkenes, providing efficient access to branched thioethers. However, this approach remains underexplored, with existing methods often hampered by limitations such as the reliance on silane reductants, the need for specialized sulfide nucleophiles or radical acceptors, or the use of external oxidants. Herein, we report a new light-promoted cobalt-catalyzed system that employs Hantzsch ester as a mild hydride source for the radical Markovnikov hydrothiolation of alkenes using N-arylsulfenyl phthalimides as thiyl radical precursors. Notably, when allylic arenes were employed as substrates, a metal-hydride hydrogen atom transfer (MHAT)/retro-MHAT process occurred, enabling the synthesis of branched benzyl sulfides, which was unattainable under conventional catalytic conditions. Mechanistic investigations support the proposed reaction pathway. This method exhibits excellent regioselectivity, broad functional group compatibility, and applicability in late-stage functionalization.