Asymmetric synthesis of pyrrolo[2,3–b]indole scaffolds by organocatalytic [3 + 2] dearomative annulation

Abstract

An organocatalytic approach for the stereoselective synthesis of pyrrolo[2,3–b]indoles is presented. The developed methodology is based on the [3 + 2] dearomative annulation reaction between 3-nitroindoles and fumaric acid amide esters. Products bearing three adjacent stereogenic centers, one being quaternary, were formed with excellent yields, good diastereoselectivities and decent enantioselectivities.