Probing Diazo Compounds for Electro-Cascade Thiolation/Cyclization/Reduction Sequence

Diazo compounds have extensively been investigated under light or metal-mediated conditions to carry out carbene-mediated transformations. In the search for novel reactivity, investigating these dinitrogen substrates under electrochemical conditions remained underexplored. Herein, we have explored diazo compounds under electrochemical conditions to establish a cascade sequence of thiolation/cyclization/reduction reactions. Electrolyzing styryl diazo imides and aryl thiols enables direct access to a single diastereoisomer of 2,5-pyrrolidine-dione-fused thiochromans in good yields under mild and metal-free conditions. Notably, a tunable reactivity was achieved via S-H insertion at the diazo center in slightly modified reaction conditions. Based on the experimental evidences, including the detection of key intermediates and computational studies, the mechanism for the electrochemical cascade reaction has also been established.