Reactions of Diazoketones in the Presence of Metal Chelates. I. Reactions in Alcohols

The reaction of diazoacetophenone with alcohols has been studied in the presence of metal chelates. Metal chelates, such as bis(acetylacetonato)copper(II), bis(acetylacetonato)nickel(II), and bis(acetylacetonato)lead(II), were found to be active catalysts for this reaction; they modified the reaction to give alkoxyacetophenones instead of alkyl phenylacetates. When tertiary amines, such as triethylamine, pyridine, and quinoline, were added to the reaction mixture, the formation of alkoxyacetophenones was suppressed and that of alkyl phenylacetates was promoted in proportion to the increase in the amount of amines added. The mechanism of the reaction can reasonably be explained by assuming the intermediacy of a ketocarbene-metal chelate complex.