Solvent dependent fluorinative cyclizations of o-hydroxy-arylenaminones promoted by H2O and NFSI: switchable access to di- and monofluorinated 2-hydroxyl chromanones

Abstract

Integrating fluorine into heterocyclic structures via cyclization reactions under metal-free conditions is attractive for organic synthesis. Herein, we describe solvent dependent fluorinative cyclizations of o-hydroxyarylenaminones, which were promoted by H₂O and NFSI under metal-free conditions, to furnish 2,3-substituted chromanones. Di- and monofluorinated 2-hydroxyl chromanones could be achieved selectively in a THF–H₂O or EtOH–H₂O system at ambient temperature under an air atmosphere.