Regioselective Radical Arylation of 3‑Hydroxypyridines

The titanium­(III)-mediated radical arylation of 3-hydroxypyridines was found to proceed with high regioselectivity for the 2-position. Using aryldiazonium chlorides, which were prepared from the corresponding anilines, as aryl radical sources, a range of 3-hydroxy-2-phenyl­pyridines were obtained in moderate to good yields under simple reaction conditions. Reactions of ortho-carboxylic ester substituted phenyl­diazonium salts directly provided tricyclic benzopyranopyridinones.