Single-electron transfer enables enantioselective synthesis of spirooxindoles via dual copper and phosphoric acid catalysis

The single-electron transfer-induced oxidative transformation of indoles has been extensively explored in recent years. However, research toward high enantioselective control in this reaction is rare. Herein, we report an enantioselective catalytic single-electron transfer-induced oxidative rearrangement of cyclic indoles enabled by dual chiral copper/phosphoric acid catalysis. Using atmospheric oxygen (O 2 ) as the terminal oxidant, the reactions of tetrahydro- β -carbolines, tetrahydropyrano[3,4- b ]indoles and the challenging tetrahydrocarbazoles are all realized, providing diverse rearrangement products including pyrrolidinyl-, tetrahydrofuranyl- and cyclopentyl-bearing spiroindolinones in good yields with high enantioselectivities. The synthetic utility of this protocol was demonstrated in a concise synthesis of (+)-coerulescine and (+)-horsfiline. These findings would provide new insights and opportunities for future asymmetric oxidative radical reaction design. A general, unified copper/CPA co-catalyzed enantioselective SET-induced oxidative rearrangement of cyclic indoles has been developed, providing diverse rearrangement products including pyrrolidinyl-, tetrahydrofuranyl- and cyclopentyl-bearing spiroindolinones in good yields with high enantioselectivities.