Chiral Nitroxide/Copper-Catalyzed Aerobic Oxidation of Alcohols: Atroposelective Oxidative Desymmetrization.

A series of chiral imidazolidinone-based hydroxylamines e.g., I were evaluated as catalysts for the aerobic oxidn. of benzyl alc./axially-prochiral diols 2,6-(CH2OH)2C6H3X [X = 2-F3CC6H4, 2-(CH3)3C-6-H3CC6H3O, 1-naphthyl] in the presence of CuOTf/bpy/NMI as co-catalysts. In such conditions, the in situ produced nitroxides catalyze the oxidn. of benzyl alc. When the imidazolidinone ring is substituted by a copper-coordinating heterocycle, the outcome of the oxidn. is clearly improved in terms of rate and maximal conversion. Enantiopure catalysts featuring a bipyridine unit covalently attached in close vicinity to the hydroxylamine could be readily prepd. and used in the enantioselective aerobic oxidn. of three model axially-prochiral diols. These results demonstrate for the first time the validity of a O2/chiral nitroxide/copper combination for enantioselective oxidns.

Références

Titre
Chiral Nitroxide/Copper-Catalyzed Aerobic Oxidation of Alcohols: Atroposelective Oxidative Desymmetrization.
Type de publication
Article de revue
Année de publication
2017
Revue
ChemistrySelect
Volume
2
Pagination
443–450
ISSN
2365-6549
Soumis le 12 avril 2018