Copper-Catalyzed Redox Deacylation of Isomeric N- and O-Benzoylhydroxylamines

Article abstract of DOI:10.1021/jo00049a016

N- and O-benzoylhydroxylamines are, in principle, capable of forming five-membered metal chelates structurally similar to those of α-amino esters.Because α-amino esters are hydrolyzed by many metal ions, the metal-promoted or -catalyzed reactions of N- and O-benzoylhydroxylamines were examined.Two metals that are active with α-amino esters - Ni(II) and Zn(II) - show no reaction with either benzohydroxamic acid or O-benzoylhydroxylamine in aqueous solution.Cu(II) accelerates the rate of benzoic acid formation with both compounds by factors of up to 60- and 40-fold, respectively, under the conditions evaluated.Both reactions give benzoic acid as product, but hydroxylamine is not a product in either reaction.We observe that O-benzoylhydroxylamine reacts with Cu(II) with net oxidation and with Cu(I) with net reduction of the nitrogenous product.When a substoichiometric amount of Cu(II) is used, copper serves as a catalyst to effect deacylation with redox disproportionation of the starting material.