Quantum-chemical study of organic reaction mechanisms. XI. The
interaction of diformylhydrazine with o- and p-aminophenols producing
biologically active 4-substituted 1,2,4-triazoles
A mechanism for the reaction of diformylhydrazine with o- and
p-aminophenols has been studied by quantum-chemical calculations within
the framework of electron density functional theory using the
B3LYP/6-311++G (d,p)//B2PLYP/6-311++G (d, p) basis sets. It is shown
that the first stage of this reaction involves nucleophilic addition of
the aminophenol nitrogen to one of the carbonyl groups of
diformylhydrazine to afford an unstable geminal amino alcohol, which can
be further dehydrated to iminohydrazide or hydrazonamide. The
prototropic imino-amine rearrangement occurring in the iminohydrazide
delivers hydrazonamide, The latter, owing to nucleophilic attack of the
nitrogen atom at the second carbonyl group, is converted into a cyclic
amino alcohol, dehydration of which produces the target 1,2,4-triazole.
The obtained results have been compared with the data NMR spectroscopy.