Electrophilic Fluorine-Mediated Povarov Cyclization: Access to Fluorinated Quinolines via in Situ Generated Fluoroketenimines.

Electrophilic fluorine-mediated synthesis of mono- and difluorinated quinolines is developed via a Povarov-type cycloaddition. The reaction involves the in situ generation of highly reactive fluoroketenimine intermediates from readily accessible phosphorus ylides under metal-free and mild conditions. The electrophilic fluorinating reagent functions as both a fluorine source and an oxidant, enabling a one-pot, step-economic cascade process. This protocol exhibits broad functional group compatibility and delivers a wide array of fluorinated quinoline derivatives in good to excellent yields. Gram-scale preparation and late-stage modification of pharmaceutical scaffolds further validated the synthetic utility of this approach.