Assembly of Substituted Phenothiazines by a Sequentially Controlled CuI/ L‐Proline‐Catalyzed Cascade CS and CN Bond Formation

In the pro-line of fire: A general and efficient cascade reaction approach to substituted phenothiazines, which relies on controlled sequential CuI/L-proline-catalyzed CS and CN bond formations, is described. DMSO=dimethylsulfoxide.