Mild, Redox-Neutral Formylation of Aryl Chlorides via Photocatalytic Generation of Chlorine Radicals

We report a redox-neutral formylation of aryl chlorides that proceeds through selective 2-functionalization of 1,3-dioxolane via nickel and photoredox catalysis. This scalable, benchtop approach provides a distinct advantage over traditional reductive carbonylation in that no carbon monoxide, pressurized gas, or stoichiometric reductant is employed. Mild conditions enable unprecedented scope from abundant and complex aryl chloride starting materials. Aromatic aldehydes are generated from abundant aryl chlorides via nickel-photocatalyzed C–H functionalization of the inexpensive solvent 1,3-dioxolane. The absence of pressurized carbon monoxide and a stoichiometric reductant enables broad functional group tolerance and scope.