Switchable α‐Chalcogenocyanation and Chalcogenation of α‐Oxo Ketene Dithioacetals

Abstract The switchable α‐chalcogenocyanation and chalcogenation of α‐oxo ketene dithioacetals (DTAs) and NH 4 SCN/KSeCN have been developed by controlling reaction conditions. α‐Chalcogenocyanation reaction smoothly occurs in the presence of 2.0 equiv of CuBr 2 at 25 °C in CH 3 CN, to give vinyl thio/ selenocyanates in excellent yields, while vinyl thioethers/selenides were obtained in moderate yields when the chalcogenation reaction is efficiently run in the presence of 3.0 equiv of CuBr 2 in refluxing CH 3 OH. The switchable chalcogenocyanation and chalcogenation of DTAs have not been previously reported, and thus the method is of much significance. In addition, plausible mechanistic pathways for the switchable chalcogeno‐cyanation and chalcogenation of DTAs are also demonstrated.