N-heterocyclic carbene catalyzed highly chemoselective intermolecular crossed acyloin condensation of aromatic aldehydes with trifluoroacetaldehyde ethyl hemiacetal.

A highly chemoselective intermolecular crossed acyloin condensation between aromatic aldehydes and trifluoroacetaldehyde ethyl hemiacetal has been developed under mild reaction conditions using N-heterocyclic carbene as a catalyst. A wide range of aromatic aldehydes bearing electron-withdrawing and -donating substituents underwent a smooth transformation to their corresponding trifluoromethyl containing acyloin derivatives in moderate to good yields.