A tautomeric ligand enables directed C‒H hydroxylation with molecular oxygen

Easing oxygen into arenes Although oxygen is all around us, it is often surprisingly difficult to use it for selective chemical oxidations, necessitating more expensive, wasteful alternatives. Li et al. report that careful ligand optimization produces palladium catalysts that can efficiently activate oxygen to hydroxylate a variety of aryl and heteroaromatic rings adjacent to a carboxylic acid substituent. The ligand binds to palladium through pyridine and pyridone components, and the authors posit that tautomerization between dative and anionic coordination modes plays a role in its effectiveness. Science , abg2362, this issue p. 1452