Electrode

Organic chemistry

Combinatorial chemistry

Ring (chemistry)

Stereochemistry

Catalysis

Physical chemistry

Indole test

Stereoselectivity

Chemistry

Functional group

Indoline

Annulation

Polymer

Electrochemistry

Angewandte Chemie International Edition

Dearomative annulation of indoles has emerged as a powerful tool for the preparation of polycyclic indoline‐based alkaloids. Compared with well‐established methods towards five‐membered‐ring‐fused indolines, the six‐membered‐ring‐fused indolines are rarely accessed under thermal conditions. Herein, a dearomative [4+2] annulation between different indoles is developed through an electrochemical pathway. This transformation offers a remarkably regio‐ and stereoselective route to highly functionalized pyrimido[5,4‐ b ]indoles under oxidant‐ and metal‐free conditions. Notably, this electrochemical approach maintains excellent functional‐group tolerance and can be extended as a modification tactic for pharmaceutical research. Preliminary mechanism studies indicate that the electrooxidation annulation proceeds through radical–radical cross‐coupling between an indole radical cation and an N‐centered radical generated in situ.

Electrooxidation Enables Selective Dehydrogenative [4+2] Annulation between Indole Derivatives