Rhodium-catalyzed regioselective arylation of phenylazoles and related compounds with arylboron reagents via C-H bond cleavage

The rhodium-catalyzed direct ortho-arylation reactions of phenylazoles using arylboron reagents such as tetraarylborates were examined. Ethyl chloroacetate and potassium fluoride were found to effectively act as a hydrogen acceptor and a promoter, respectively, to afford selective formation of the corresponding mono- or diarylated products with good yields. In addition, azobenzene as well as 2-phenylpyridine also underwent the direct arylation under similar conditions. (C) 2008 Elsevier B.V. All rights reserved.