Selective Modular Synthesis of ortho-Substituted Phenols via Pd- Catalyzed Dehydrogenation-Coupling-Aromatization of Alcohols

Phenols are pivotal precursors and core motifs for various fine chemicals, bioactive molecules, and functional materials, among which the site-selective syntheses of ortho- substituted phenols are very attractive and challenging. Here, we present a palladium-catalyzed dehydrogenation-coupling-aroma-tization protocol to access ortho-substituted phenols from cyclohexanols with primary alcohols. Broad substrate scope was achieved in this modular protocol with water and hydrogen gas as clean byproducts. The ortho-mono-and ortho-disubstitutions were readily controlled by N-heterocyclic carbene (NHC) ligands and the amount of base.