Addition–Rearrangement of Ketenes with Lithium N - tert -Butanesulfinamides: EnantioselectiveSynthesis of α,α-Disubstituted α‑HydroxycarboxylicAcid Derivatives

Addition of the lithium salts of chiral N-substituted tert-butanesulfinamides to ketenes and subsequent silylation initiates stereoselective [2,3]-rearrangement, which affords enantioenriched α,α-disubstituted α-sulfenyloxy carboxamides through a reaction that faithfully transfers the absolute stereochemistry of the lithiated sulfinylamides to the α-carbon of the amide products. This addition–rearrangement can be performed together with ketene formation from acyl chloride in a single flask, providing a new and practical synthetic route to α-hydroxycarboxylic acid derivatives.