Indium(I) bromide-promoted stereoselective preparation of (E)-α,β-unsaturated ketones via sequential intermolecular aldol-type coupling/elimination reactions of α,α-dichloroketones with aldehydes

Indium(I) bromide promotes the reaction of α,α-dichloroketones with aldehydes to produce (E)-α,β-unsaturated ketones, exclusively. The transformation occurs via two sequential reactions, an aldol-type coupling between the two carbonylic reagents followed by an elimination process.