MECHANISM FOR THE OXIDATIVE CLEAVAGE OF ELECTRON-DEFICIENT ACETYLENES WITH ALKALINE HYDROGEN PEROXIDE.

Article abstract of DOI:10.1246/bcsj.56.1133

4-Phenyl-3-butyn-2-one was effectively cleaved by alkaline hydrogen peroxide to afford benzoic and acetic acids. The rate ratio for the addition of HOO** minus and HO** minus resulted in k//H//O//O-/k//H//O- equals 1400, which is comparable to that of benzylideneacetone. The major reaction of the cleavage proceeds via benzoylacetone. As a minor pathway, alpha -keto oxirene intermediate is formed and rearranges only to alpha -benzoylproprionate in a different way from the corresponding diketo carbene. alpha //-Keto esters are found to be converted by HOO** minus to alpha -alkoxy ketones via a novel oxidative substitution of ester group. The mechanism is discussed on the basis of oxirene intermediate inconvertible to keto carbene.