Rare earth triflates/chlorotrimethylsilane induced activation of triethylamine as a latent acetaldehyde anion: a new synthesis of α,β-unsaturated aldehydes

A synthetic methodology for α,β-unsaturated aldehydes employing rare earth triflate is reported. Activated triethylamine reacts with aldehydes to form two carbon extended aldehydes, which is promoted by a catalytic amount of Yb, Sc, Y, and In(OTf)3, in the presence of chlorotrimethylsilane. We investigated the conditions applicable to aromatic aldehydes as well as heterocyclic compounds as substrates. A deuterium labeling experiment supported our proposed reaction mechanism.