title: Highly efficient aerobic oxidation of alcohols by using less-hindered nitroxyl-radical/copper catalysis: optimum catalyst combinations and their substrate scope.
abstract: The oxidation of alcohols into their corresponding carbonyl compounds is one of the most fundamental transformations in organic chemistry. In our recent report, 2-azaadamantane N-oxyl (AZADO)/copper catalysis promoted the highly chemoselective aerobic oxidation of unprotected amino alcohols into amino carbonyl compounds. Herein, we investigated the extension of the promising AZADO/copper-catalyzed aerobic oxidation of alcohols to other types of alcohol. During close optimization of the reaction conditions by using various alcohols, we found that the optimum combination of nitroxyl radical, copper salt, and solution concentration was dependent on the type of substrate. Various alcohols, including highly hindered and heteroatom-rich ones, were efficiently oxidized into their corresponding carbonyl compounds under mild conditions with lower amounts of the catalysts.
authors.affiliation: Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578 (Japan).
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sasano
authors.forename: Naoki
authors.initials: N
authors.lastname: Kogure
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nishiyama
authors.forename: Shota
authors.initials: S
authors.lastname: Nagasawa
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Iwabuchi
mesh_terms: D000438:Alcohols / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D000438:Alcohols; D009589:Nitrogen Oxides; D003300:Copper; C039900:nitroxyl
keywords: alcohols; copper; homogeneous catalysis; oxidation; radicals