Al Lewis Acid-Catalyzed Regiodivergent 1,2-Rearrangement of α-Siloxy Aldehydes: Scope and Mechanism.

Regiodivergent 1,2-rearrangement of α-siloxy aldehydes bearing α-aryl and α-alkyl substituents into α-siloxy ketones has been realized by using different Al Lewis acid catalyst/solvent systems. The scope of this unprecedented protocol has been investigated with various substrates, clearly demonstrating its utility for the selective synthesis of two structural isomers from one substrate. Controlled experiments proved that the regiodivergency resulted from the switch of the migrating group.