Synthesis of Benzo[ c]cinnolinium Salts from 2-Azobiaryls by Copper(II) or Electrochemical Oxidation

Huan-Chang Hsiao; Meng-Che Li; Guganchandar Vedarethinam; Pei-Lin Chen; Shih-Ching Chuang

doi:10.1021/acs.orglett.4c00213

Synthesis of Benzo[ c]cinnolinium Salts from 2-Azobiaryls by Copper(II) or Electrochemical Oxidation

Org Lett. 2024 Mar 1;26(8):1694-1698. doi: 10.1021/acs.orglett.4c00213. Epub 2024 Feb 15.

Authors

Huan-Chang Hsiao¹, Meng-Che Li¹, Guganchandar Vedarethinam¹, Pei-Lin Chen¹, Shih-Ching Chuang¹

Affiliation

¹ Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.

Abstract

Synthesis of benzo[c]cinnolinium salts by copper(II)-promoted or electrochemical oxidation of 2-azobiaryls is described. A variety of diversely functionalized benzo[c]cinnolinium salts were easily constructed by this strategy with excellent functional group tolerance and high efficiency. An interesting fluorescence centered at 571 nm is revealed by a benzo[c]cinnolinium salt with electron push-pull substitutions. The mechanism is proposed to go through single-electron transfer driven by oxidant and intramolecular cyclization via nucleophilic addition, followed by an anion exchange.