A General Photoactive H‐Bonding EDA Complex Model Drives the Selective Hydrothiolation and Hydroxysulfenylation of Carbonyl Activated Alkenes

Excitation of photoactive electron donor−acceptor (EDA) complexes to generate radical is a promising approach in radical chemistry. In this study, we introduce a new model of H‐bonding EDA complexes for the selective hydrothiolation and hydroxysulfenylation of carbonyl‐activated alkenes with diverse thiols under visible light conditions. The reliability of this H‐bonding EDA complex model has been confirmed by meticulous experimental and theoretical calculations. Mechanistic investigations have revealed the significant influence of the solvent in determining whether the excitation of photoactive H‐bonding EDA complex leads to charge transfer (CT) or energy‐charge transfer (En‐CT), thereby controlling Markovnikov and anti‐Markovnikov selectivity. Notably, the Quantum Theory of Atoms in Molecules (QTAIM) analysis clearly shows that the excited state of the C＝O‐‐‐H‐S EDA complex involves closed‐shell partially covalent interactions.