A Synthetic Route to Chiral Tetrahydropyrroloindoles via Ring Opening of Activated Aziridines with 2‑Bromoindoles Followed by Copper-Catalyzed C–N Cyclization

A new synthetic route to nonracemic tetrahydropyrrolo­[2,3-b]­indoles has been developed via S_N2-type ring opening of enantiopure N-activated aziridines with 2-bromoindoles followed by copper-catalyzed C–N cyclization. A series of N-activated aziridines and 2-bromoindole derivatives with different substitution patterns were studied to afford the corresponding tetrahydropyrrolo­[2,3-b]­indoles in good yields and excellent ee (up to 99%). Highly substituted tetrahydropyrrolo­[2,3-b]­indole was synthesized as a single stereoisomer (de, ee >99%) from enantiopure trans-disubstituted aziridine.