Highly Diastereoselective Synthesis of Dihydro‐benzoimidazo‐[1,3]‐thiazines via Electro‐oxidative Selenocyclization of Thioallyl Benzoimidazoles

The current methodology reveals a green and proficient electro‐oxidative tandem selenocyclization of thioallyl benzoimidazoles manufacturing selenylated dihydro‐benzoimidazo‐thiazine derivatives. Both C−Se and C−N bond formation were achieved via this mild protocol which exhibits good functional group tolerability affording an extensive range of substrate scope up to 96% isolated yields. Complete control over the regioselective formation of the six‐membered heterocycle and stereoselective construction of the contiguous stereocenters was established. The practical electrochemical method operates in an undivided cell at ambient temperature without using any metal and external chemical oxidant. A series of dihydro‐benzoimidazo‐thiazine derivatives displaying exclusive diastereoselectivity has been synthesized proficiently via external chemical oxidant and metal‐free selenocyclization methodology. This mild electro‐oxidative protocol operates in an undivided electrochemical cell at ambient temperature under air, exhibiting decent functional group tolerance and excellent yields.