Chiral Brønsted Acid‐Promoted Enantioselective Desymmetrization in an Intramolecular Schmidt Reaction of Symmetric Azido 1,3‐Hexanediones: Asymmetric Synthesis of Azaquaternary Pyrroloazepine Skeletons

The enantioselective desymmetrization of 2-substituted-2-azidopropyl 1,3-hexanediones through an asymmetric intramolecular Schmidt reaction using a chiral Brønsted acid has been developed for the first time. Synthetically interesting pyrroloazepine skeletons with an azaquaternary stereogenic center with up to 59 % ee are accessed effectively (see scheme; R=H, alkyl, or aryl).