Photoinduced Deoxygenative Halocarbocyclization of Aldehyde Enabled by Tertiary Phosphine

The development of transition-metal-free protocols for the deoxygenative difunctionalization of carbonyls represents a significant challenge in organic synthesis. Herein, we report a photochemical strategy for deoxygenative difunctionalization of γ-enal by leveraging the reactivity of phosphine–iodide EDA complexes. Mechanistic studies indicate that the reaction proceeds through single-electron transfer within EDA complexes, addition of the fluoroalkyl radical to a C═C bond, 5-exo-trig cyclization, radical–radical cross-coupling between an in situ-generated alkoxy radical and phosphine radical cation, and SN2 substitution. This method features a broad substrate scope and high step economy, offering a robust platform for the rapid assembly of complex functionalized carbocycles.