Reactions of lead tetra-acetate. Part VI. Further reactions with hydrazones

Abstract

The azoacetates derived from the oxidation of benzil phenyl- and p-nitrophenyl-hydrazone with lead tetra-acetate react differently with boron trifluoride compared with the azoacetates obtained from aromatic ketone arylhydrazones. The phenyl-derivative gives mainly NN′-dibenzoylphenylhydrazine via a rearrangement, whereas the p-nitrophenyl-derivative gives N-acetyl-N′-benzoyl-p-nitrophenylhydrazine with the loss of a benzoyl group. The latter product is also obtained directly from benzoin p-nitrophenylhydrazone and lead tetra-acetate. Benzophenone benzyl-, benzoyl-, and p-nitrobenzoylhydrazone react with lead tetra-acetate with the loss of nitrogen, the benzyl-derivative giving 1,1,2-triphenylethyl acetate and the aroyl-derivatives giving epoxides. Benzophenone toluene-p-sulphonyl-hydrazone in methylene dichloride is converted into benzophenone but, when methanol is also present, into benzophenone dimethylketal. Possible mechanisms for these reactions are discussed.