One‐Pot Synthesis of Cycloocta[<i>b</i>]indole Through Formal [5+3] Cycloaddition Using Donor–Acceptor Cyclopropanes

Abstract

A new approach to cycloocta[ b ]indole through formal [5+3] cycloaddition was developed. This methodology was realized by using an indole derivative as a C5 unit and a cyclopropane derivative as a C3 unit. These two units have both donor and acceptor properties. Two carbon–carbon bonds were formed stepwise by the successive addition of a Lewis acidic catalyst and a Brønsted base. The reaction could be performed as a one‐pot process. Optically active cycloocta[ b ]indole was also synthesized by using this methodology with a chiral cyclopropane as a C3 substrate.