Copper‐Catalyzed Intramolecular Radical Amination of Tertiary C(sp3)−H Bonds to Access α‐Quaternary Pyrrolidines

Abstract

AbstractHerein, we describe a Cu(I)/phosphoric acid catalyzed intramolecular radical tertiary C(sp3)−H amination of N‐chlorosulfonamide, providing an applicable route to the pyrrolidine structural motifs bearing an α‐quaternary stereocenter (>20 examples with up to 94 % yield). Mechanistic studies indicate that the reaction involves an intramolecular 1,5‐hydrogen atom transfer process to form the key tertiary C‐centered radical followed by a C−N bond formation. The corresponding enantioselective amination is accordingly disclosed by Cu(I)/chiral phosphoric acid catalyst to afford the chiral products with up to 81 % enantiomeric excess (ee). This strategy is anticipated to facilitate the development of tertiary C(sp3)−H functionalization.