Enantioselective Arylation of Tetrasubstituted Enamines: Access to Enantioenriched Indolenine and 1H-Indole Derivatives

Palladium-catalyzed intramolecular enantioselective β-arylation of tetrasubstituted endocyclic and exocyclic enamines is developed. A range of optically active medium-ring fused indolenines or 3,3′-spiroindolenines were achieved in enantiomeric ratios up to 98:2 with Cs₂CO₃ or K₃PO₄ as the base in the presence of chiral PHOX ligands. The use of Ag₃PO₄ as a base led to enantioenriched 1H-indoles in good enantiomeric ratios (up to 89:11) with (S)-DIFLUORPHOS as a chiral ligand, which proceeded via a possible domino enamine-isomerization/β-arylation sequence.