Enantioconvergent Deacylative Functionalization toward α‐Quaternary Nitriles

Abstract The use of readily available prochiral or racemic quaternary carbons to access enantioenriched ones offers a promising alternative to conventional synthesis from tertiary or planar substrates. Unlike desymmetrization, which modifies an existing substituent with limited reactivity, a functional group swap can install a new motif, which is structurally distinct and nonderivable from the replaced group. However, achieving enantioconvergence in these quaternary‐to‐quaternary transformations is challenging, especially for acyclic stereocenters. Here, we report that acyl groups of β‐ketonitriles can be stereoselectively replaced by allyl, propargyl, or benzyl moieties using easily accessible alcohols under palladium catalysis. The deacylative functionalization proceeds through a retro‐Claisen‐type elimination of ketonitrile with alkoxide and the absence of diastereoisomerism in the resulting ketenimine anion assists the subsequent asymmetric addition. Together with the pair of α‐substituents, the retained nitrile and the incoming alkyl motif instill significant derivatization potential into the enantioenriched quaternary stereocenters.