Facile and fast pinacol rearrangement by AlCl3 in the solid state

A facile and efficient synthetic procedure for effecting the pinacol rearrangement catalyzed by AlCl3 in the absence of solvent is developed. The rearrangement product is obtained at room temperature in a few minutes and in almost quantitative yield. Benzylic pinacols rearrange under these conditions, while aliphatic pinacols do not react.