Complete switch of migratory aptitude in aluminum-catalyzed 1,2-rearrangement of differently α,α-disubstituted a-siloxy aldehydes

(Chemical Equation Presented) Control of the migration tendency: The regiodivergent 1,2-rearrangement of asiloxy aldehydes bearing α-aryl and α-alkyl substituents into α-siloxy ketones has been realized by using different aluminum Lewis acid catalyst/solvent systems (see scheme). The scope of this unprecedented protocol has been investigated with various substrates and clearly demonstrates its utility for the selective synthesis of two structural isomers from one substrate.