Visible light-mediated, multicomponent, regioselective phosphinylalkylation of indoles with readily available carbonyl compounds and diaryl phosphine oxides at ambient temperature is demonstrated. The strategy presented here is also effective with anilines. Key to this transformation is the electron-donor-acceptor (EDA) complex formation between the in situ generated (vinylogous) iminium intermediate and secondary phosphine oxides. Mechanistic studies supported the EDA complex-enabled radical pathway.
Banu et al. (Fri,) studied this question.