[1,2]-Carbon to Carbon Silyl Migration for Accessing α-Silyl Alkanals from α-Hydroxy Allyl Silanes

An acid-catalyzed [1,2]-carbon-to-carbon silyl migration is reported for the synthesis of α-silyl aldehydes from α-hydroxy allyl silanes, which can serve as valuable precursors for various organic reactions. During the synthesis of α-hydroxy allyl silanes, an unexpected aldehyde peak in NMR suggested an in situ rearrangement, later confirmed to be acid-driven. Expanding the substrate scope revealed that an alkyl substituent at the β-position was crucial for migration. Mechanistic studies indicated a stepwise process via a carbocation intermediate, as confirmed by stereochemical erosion in enantiomerically enriched substrates. The tertiary carbocation is further stabilized by the β-silicon effect. The advantages of this method include mild reaction conditions, clean conversion, and often no need for purification.