Organophotocatalyzed Radical Hydrophosphonylation of Acrylates, α,β-Unsaturated Ketones, Coumarins, Quinoxalinones, and <i>p</i>-Quinone Methides

An efficient and general organophotocatalytic protocol for the hydrophosphonylation of electron-deficient alkenes is reported. Thioxanthone catalyzed generation of phosphonyl radicals from <i>H</i>-phosphine oxides enabled expeditious access to a range of β-phosphonylated esters, ketones, nitriles, amides, and γ-ketophosphine oxides, in excellent yields. This protocol features simple operating conditions, proceeds under mild conditions, provides access to an impressive array of diverse structural scaffolds, and exhibits broad functional group tolerance.