Umpolung of o-Hydroxyaryl Azomethine Ylides: Entry to Functionalized γ-Aminobutyric Acid under Phosphine Catalysis

A phosphine-catalyzed reaction between o-hydroxyaryl azomethine ylides and MBH carbonates provides access to highly functionalized γ-aminobutyric acid derivatives in moderate to good yields. Mechanistically, the reaction involves a phosphine-catalyzed tandem SN2'/2-aza-Cope rearrangement/intramolecular addition process.