Abstract
Herein, we report a reductive cross-coupling reaction of alpha-oxy halides, simply generated from aldehydes, with a series of C(sp(2))- and C(sp)-electrophiles. A wide range of aryl and heteroatom aryl halides, vinyl bromides, alkynyl bromides, and acyl chlorides react with unhindered and hindered aldehyde-derived alpha-oxy halides by providing protected alcohols as well as alpha-hydroxy ketones. Noteworthy, the reductive couplings are achieved not only through thermal catalysis with the use of metal reductants but also by photocatalysis, electrochemistry, and mechanochemistry. The unrestricted interchange of the four strategies indicates their underlying mechanistic similarities. The generation of Ni-I intermediate is proposed to be the key point for ketyl radical formation via a single-electron transfer (SET) event, which was rationalized by an array of control experiments and density functional theory (DFT) calculations.