Cu-Catalyzed Domino Synthesis of Indolines

Significance

A general domino Cu-catalyzed amidation-intramolecular nucleophilic substitution process leading to indolines in good to excellent yields under very mild conditions is described. In the purported nucleophilic substitution step, mesylates rather than iodo and chloro derivatives were found to be the best substrates. Three mechanistic pathways proceeding via intermediates A-C were proposed. The formation of enantiopure D and racemic cis-E with complete inversion from the corresponding starting materials strongly suggests pathway C to be the operative mechanism.