Single-electron reduction of a carbonyl to a ketyl enables access to a polarity-reversed platform of reactivity for this cornerstone functional group. However, the synthetic utility of the ketyl radical is hindered by the strong reductants necessary for its generation, which also limit its reactivity to net reductive mechanisms. Herein, we report a strategy for net redox-neutral generation and reaction of ketyl radicals. The in situ conversion of aldehydes to α-acetoxy iodides lowers their reduction potential (Δ 1200 mV), allowing for milder access to the corresponding ketyl radicals and an oxidative termination event. Upon subjecting these iodides to a Mn2(CO)10 pre-catalyst and visible light irradiation, an atom transfer radical addition (ATRA) mechanism affords a broad scope of vinyl iodide products with high Z-selectivity.

A unified strategy enables multi-component radical addition cascades to couple alkenes, heteroarenes, and various radicals, including N3, P(O)R2, and CF3.

A polarity-reversing radical cascade strategy for alkene di-functionalization by vicinal C-C and C-P bond-formation has been developed. This approach to concurrently adding phosphorous and a heteroarene across an olefin is enabled by photocatalytic generation of electrophilic P-centered radicals. Upon chemoselective addition to an olefin, the resulting nucleophilic C-centered radical selectively combines with electrophilic heteroarenes, such as pyridines. This multi-component coupling scheme for phosphinylalkylation complements classic two-component methods for hydrophosphinylation of alkenes and C-H phosphinylation of arenes. Included competition and photo-quenching experiments provide insight into the selectivity and mechanism of this polarityreversal pathway.