An environmentally benign and efficient method has been developed for the synthesis of phenothiazines via a tandem iron-catalyzed C-S/C-N cross-coupling reaction. Some of the issues typically encountered during the synthesis of phenothiazines in the presence of palladium and copper catalysts, including poor substrate scope, long reaction times and poor regioselectivity, have been addressed using this newly developed iron-catalyzed method.

A potassium carbonate-mediated tandem coupling reaction for the synthesis of phenothiazines is described. This protocol affords an efficient approach for the construction of phenothiazine derivatives without the need for addition of transition-metal catalyst or ligand.

The synthesis of benzoxazoles via an iron-catalyzed cascade C–N and C–O coupling is described.

A practical and efficient method for N-arylation of benz­amides promoted by potassium carbonate in the presence of DMEDA was developed. The reaction was carried out without addition of any transition-metal catalyst to afford a variety of N-arylated products in moderate to good yields (up to 97%).