Ortho- and Para-Selective Ruthenium-Catalyzed C(sp2)–H Oxygenations of Phenol Derivatives
摘要:
Versatile ruthenium catalysts allowed for efficient direct oxygenations of aryl carbamates under remarkably mild reaction conditions. In addition to chelation-assisted C-H activation, the optimized ruthenium catalyst proved amenable to para-selective hydroxylations of anisoles without Lewis basic directing groups.
N-heterocyclic carbene ligands in nickel-catalyzed Suzuki–Miyaura cross-coupling of aryl esters and carbamates is investigated. Imidazol-2-ylidene bearing 2-adamantyl groups at its nitrogen atoms generates the most active nickel species among the ligands examined, allowing cross-coupling of a range of aryl carbamates and pivalates. Unlike the previously reported systemusing tricyclohexylphosphine, this protocol