Electrosynthesis of 1,2,5‐Thiadiazines via Three‐Component Annulation of Isocyanides, Elemental Sulfur, and Diamines

1,2,5‐Thiadiazines, a class of six‐membered heterocycles containing two nitrogen atoms and one sulfur atom, have been widely incorporated into various biologically active molecules. Herein, we report a green and efficient electrochemical three‐component reaction of isonitriles, elemental sulfur, and diamines to access 1,2,5‐thiadiazines under mild conditions. Elemental sulfur serves as an inexpensive, readily available, stable, and nontoxic sulfur source. Both aliphatic and aryl isonitriles are suitable substrates for this strategy at room temperature, and a series of 1,2,5‐thiadiazines are prepared with up to 77% yields. In this one‐pot transformation, one C─N bond, one C─S bond, and one S─N bond are constructed with high regioselectivity, demonstrating excellent functional group tolerance and high atom economy.