Tuning the Selectivity: Study of Solvent-Free Acid-Mediated Pinacolic-Pinacolone Rearrangement under Microwave Irradiation

Here we report an efficient solvent-free pinacolic-pinacolone rearrangement using supported acids. Given a standard procedure (5 minutes microwave heating at 180 degrees C), changing the acid catalyst allow to reverse the selectivity of the reaction. The optimized conditions represent an efficient means by which pinacol-pinacolone rearrangement can be carried out while avoiding the use of strong homogeneous Bronsted acids and extended reaction times. This neat reaction gave the products in high yield, purity and ease of recovery. Moreover, the catalyst can be reused on 10 runs without any loss of activity nor selectivity. As a consequence, that protocol can be referred as a green and efficient process for pinacol-pinacolone rearrangement.