Synthesis of Unsymmetrical\nDisulfides via Photocatalytic\nHydrodisulfuration

Photoredox catalysis is an appealing strategy for the\nC–S\nbond formation. Herein, we disclose the photocatalytic reductive hydrodisulfuration\nof electron-deficient alkenes for the synthesis of unsymmetrical disulfides.\nMechanistic studies indicate that while the radical initiation occurs\nin this reaction, the perthiolate anion generated from the reduction\nof tetrasulfides via single-electron transfer is the key electron\ndonor for the conjugate addition. This methodology exhibits broad\nfunctional group tolerance and allows the late-stage installation\nof disulfide motifs into marketed drugs and the preparation of peptides\ncontaining the disulfide bond under cysteine-free conditions. Moreover,\nthe mechanism of ionic addition is further explained by control experiments\nand computations.