N-(2-aminobenzoyl)-N-methylhydrazones of aldehydes and aldoses and their cyclization to benzo-1,3,4-triazepine derivatives

The products of the condensation of aliphatic aldehydes with N-(2-aminobenzoyl)-N-methylhydrazine exist in DMSO-d6 solution as tautomeric mixtures of linear aldohydrazone and cyclic benzo-1,3,4-triazepine forms. The linear tautomer predominates for 2-aminobenzoyl-N-methylhydrazones of aromatic aldehydes. A tautomeric equilibrium is observed in DMSO-d6 for the products of the condensation of the hydrazide of 2-aminobenzoic acid with a series of aldoses. This equilibrium exists between α,β-isomeric pyranose forms and the open aldosohydrazone form. Isomeric conversion to the seven-membered benzo-1,3,4-triazepine form is observed for the products of the condensation of aldoses with N-(2-aminobenzoyl)-N-methylhydrazine.