GaCl3-catalyzed skeletal rearrangement of alpha,alpha,alpha-trisubstituted aldehydes.

[Reaction: see text] GaCl3 is found to be a superior catalyst for the skeletal rearrangement of alpha,alpha,alpha-trisubstituted aldehydes to ketones. The rearrangement can proceed smoothly in the presence of a catalytic amount of GaCl3, and even substrates having no heteroatoms alpha to the carbonyl group or without steric strains can be used. Double activation of a carbonyl group by two molecules of GaCl3 was supported on the basis of experimental data and a DFT study.