Forming All‐Carbon Quaternary Stereocenters by Organocatalytic Aminomethylation: Concise Access to β2,2‐Amino Acids

Abstract

AbstractThe asymmetric synthesis of β2,2‐amino acids remains a formidable challenge in organic synthesis. Here a novel organocatalytic enantioselective aminomethylation of ketenes with stable and readily available N,O‐acetals is reported, providing β2,2‐amino esters bearing an all‐carbon quaternary stereogenic center in high enantiomeric ratios with a catalytic amount of chiral phosphoric acid. Typically, this transformation probably proceeds through an asymmetric counter‐anion‐directed catalysis. As a result, a concise, practical, and atom‐economic protocol toward rapidly access to β2,2‐amino acids has been developed.