Visible-Light-Mediated Three-Component Decarboxylative Coupling Reactions to Synthesize 1,4-Diol Monoethers

An efficient approach for 1,2-difunctionalization
of
aromatic olefins
and the synthesis of functionalized 1,4-diols monoethers has been
established via a photoinduced three-component reaction of an α-alkoxycarboxylic
acid, an aromatic olefin, and an aldehyde. The reaction proceeds by
photoinduced oxidative decarboxylation of the carboxylic acid followed
by the addition of the α-alkoxyalkyl radical to the olefin,
one-electron reduction of the addition radical, and the nucleophilic
attack of the resulting carbanion to the aldehyde. Besides the convenient
one-pot protocol of the three-component reaction, this method offers
several other advantages, including good functional group tolerance
for the three substrates, gentle reaction conditions, and ease of
scaling up. The reaction mechanism has been investigated through free
radical trapping experiment and isotope labeling experiments.