Indole macrocycles formed by diindolylmethane ring closure

Abstract

Indole containing macrocyclic compounds can be formed from suitable diindolyl diesters and diamides by acidcatalysed reaction with formaldehyde to generate a 2,2'-linkage in the ring closure step. The alternative protocol in which macrocyclisation is attempted by lactone or lactam formation from starting 2,2'diindolylmethane systems was unsuccessful in our examples.