Highly diastereoselective oxa-[3+3] cyclization with C,N-cyclic azomethine imines via the copper-catalyzed aerobic oxygenated C[double bond, length as m-dash]C bond of indoles.

Herein, a copper-catalyzed highly diastereoselective aerobic oxygenated [3+3] cyclization of 3-substituted indoles with C,N-cyclic azomethine imines using oxygen as the sole oxidant under mild conditions has been developed. This protocol provides a simple and convenient approach for constructing [2,3]-fused indoline O-heterocycles bearing two pharmaceutically intriguing parts, tetrahydroisoquinoline and indoline. Good yields and excellent diastereoselectivity under mild reaction conditions were observed.