Microwave-Assisted Synthesis of Azoniaspiro Compounds Using a Novel Catalyst, 1-Azaphenothiazine

Abstract

1-Azaphenothiazine catalyses the intramolecular cyclization of N-(bromoalkyl)phthalimides in the presence of anhydrous K₂CO₃ to form spiro cyclic quaternary ammonium salts, namely azoniaspiro compounds, under microwave irradiation. A novel and ecofriendly method was developed for the synthesis of azoniaspiro compounds, and the role of azaphenothiazine as a catalyst in such reactions has been established for the first time. In the future, this protocol can be extended to the synthesis of various substituted N-heterocycles by hydrolyzing the resulting azoniaspiro compounds.

Keywords:

• 1-Azaphenothiazine
• azoniaspiro
• catalyst
• microwave irradiation
• N-(bromoalkyl)phthalimides

ACKNOWLEDGMENTS

We thank the Department of Science and Technology, New Delhi, India, for financial support and the Council of Scientific and Industrial Research, New Delhi, India, for providing senior research fellowships to K. K. and R. S. respectively.