Copper-catalyzed oxidative selective cyclization/C–N cross-coupling of two tryptamines to access 3a-tryptamine-pyrroloindolines

Abstract

Transition-metal-catalyzed C–N bond formation reactions have been widely studied in recent decades, but site-selective intermolecular C–N cross-coupling between the carbon and nitrogen sites of two identical molecules is less explored. Herein, we report the highly selective copper-catalyzed oxidative cyclization/C–N cross-coupling of two tryptamines with O₂ as the terminal oxidant, which provides practical and direct access to a new class of indole-linked-pyrroloindoline compounds in moderate to good yields. Mechanistic studies suggested that the coordination between the copper catalyst and the tryptamine substrate is key for chemoselectivity control.