Heteroarene Phosphinylalkylation via a Catalytic, Polarity-Reversing Radical Cascade

A polarity-reversing radical cascade strategy for alkene difunctionalization by vicinal C-C and C-P bond formation has been developed. This approach to concurrently adding phosphorus 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 multicomponent coupling scheme for phosphinylalkylation complements classic two-component methods for hydrophosphinylation of alkenes and C-H phosphinylation of arenes. Included competition and photoquenching experiments provide insight into the selectivity and mechanism of this polarity-reversal pathway.