Molecular Iodine‐Mediated Cascade Reaction of 2‐Alkynylbenzaldehyde and Indole: An Easy Access to Tetracyclic Indoloazulene Derivatives

Abstract

Abstract The synthesis of iodo‐substituted tetracyclic indole fused azulene derivatives was achieved from the reaction of 2‐(substituted phenylethynyl)benzaldehydes and different indoles in the presence of molecular iodine. The reaction involves the formation of a bisindole from the corresponding 2‐(substituted phenylethynyl)benzaldehyde and indole followed by iodocyclization in a one‐pot cascade process. A wide range of 2‐(substituted phenylethynyl)benzaldehydes and indoles were utilized in this protocol to derive a diverse range of iodo‐substituted tetracyclic indole fused azulene derivatives in moderate to good yields. Further functionalizations of the iodo‐substituted tetracyclic indole fused azulenes were achieved by various palladium‐catalyzed cross‐coupling reactions to generate highly substituted tetracyclic indole fused azulene derivatives. magnified image