Base‐Metal‐Catalyzed Oxidative Cross‐Couplings Between 2‐Naphthols and Phenols or Arylamines

Unprecedented base-metal-catalyzed oxidative cross-couplings between 2-naphthols and phenols or arylamines have been described to produce 4-aryloxynaphthalene-1,2-diones and 4-(arylimino)naphthalen-1(4H)-ones in this report. With the present protocol, molecule skeletons similar to the tanshinone, 2-(2-carboxyvinyl)benzoic acid and neo-tanshinlactone can be readily accessed thus highlighting its potential use in organic synthesis and drug discovery.

Abstract

An unprecedented base-metal-catalyzed oxidative cross-coupling between 2-naphthols and phenols or arylamines has been described in this report. Acetic acid and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) are the crucial oxidative system that promotes the transformation under aerobic conditions with the assistance of base-metal salts. While ferrous sulfate was the optimal catalyst in the oxidative coupling of 2-naphthols and phenols to produce 4-aryloxynaphthalene-1,2-diones, cuprous iodide catalyst is utilized to synthesize (arylimino)naphthalen-1(4H)-ones from 2-naphthols and arylamines. Employing this protocol, molecule skeletons similar to tanshinones, 2-(2-carboxyvinyl)benzoic acid and neo-tanshinlactone can be accessed thus highlighting its potential use in organic synthesis and drug discovery.

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