Enantioselective synthesis of N-C axially chiral indoles through chiral palladium-catalyzed 5-endo-hydroaminocyclization

In the presence of (R)-SEGPHOS-PdCl2 catalyst, 5-endo-hydroaminocyclization of various 2-(tert-butyl)-N-(2-ethynylphenyl)anilines proceeds enantioselectively to afford optically active N-C axially chiral N-(2-tert-butylphenyl)indole derivatives in good yields. The enantioselectivity depends strongly on the bulkiness of ortho-substituents and the electron density on the arylethynyl group, and it is explained by the dynamic axial chirality generated by the twisting of the aryl substituent. (C) 2015 Elsevier Ltd. All rights reserved.