Synthesis of Cyclohepta[ b]indoles and Furo[3,4- b]carbazoles from Indoles, Tertiary Propargylic Alcohols, and Activated Alkynes

Org Lett. 2023 May 5;25(17):3078-3082. doi: 10.1021/acs.orglett.3c00885. Epub 2023 Apr 21.

Abstract

A robust metal-free and environmentally friendly approach to cyclohepta[b]indole and furo[3,4-b]carbazole frameworks via a three-component reaction from indoles, tertiary propargylic alcohols, and activated alkynes is described. A probable mechanism was proposed on the basis of the isolation and characterization of a key intermediate of the reaction. A gram-scale reaction and product derivatizations were also performed to demonstrate the practicality of the developed methodology.