Regioselective Transition Metal-Free Catalytic Ring Opening of 2<i>H</i>-Azirines by Phenols and Naphthols; One-Pot Access to Benzo- and Naphthofurans
Arnab Roy, Subrata Biswas, Subrata Biswas, Surajit Duari, Srabani Maity, Abhishek Kumar Mishra, Aguinaldo Robinson de Souza, Asma M. Elsharif, Nelson H. Morgon, Srijit Biswas, Srijit Biswas
Abstract
Benzofuran and naphthofuran derivatives are synthesized from readily available phenols and naphthols. Regioselective ring openings of 2 H -azirine followed by in situ aromatization using a catalytic amount of Brønsted acid have established the novelty of the methodology. The involvement of a series of 2 H -azirines with a variety of phenols, 1-naphthols, and 2-naphthols showed the generality of the protocol. In-depth density functional theory calculations revealed the reaction mechanism with the energies of the intermediates and transition states of a model reaction. An alternate pathway of the mechanism has also been proposed with computer modeling.