The Synthesis of ABNO~+BF4~- and its Application to Alcohol Oxidation

摘要

Nitroxyl radicals such as 2,2,6,6,-tetrarnethylpiperidine-iV-oxyl (TEMPO) are widely used in organic synthesis. Especially, they have played a crucial role in alcohol oxidation. A variety of alcohol oxidations using catalytic amounts of nitroxyl radicals have been developed by the virtue of secondary oxidants such as NaOCl, Br2, and PhI(OAc)2. In these catalytic alcohol oxidations, oxoammonium salts, which were afforded by one-electron oxidation of nitroxyl radicals, are active oxidants, and the alcohols undergo two-electron oxidation during two-electron reduction of oxoammonium salts to hydroxylamine species. The regeneration of oxoammonium salts through the oxidation of the hydrox-ylamines species by the oxidants completed the catalytic cycle. Oxoammonium salt-mediated alcohol oxidations using stoichiometric amounts of oxoammonium salts were also developed to avoid the use of secondary oxidants.