Abstract
α-Acetylpropionic imidoether (I) and N4-acetylsulfanilamide (IIa) or sulfanilamide (IIb) undergo selective dealcoholation-condensation at N1-position of (II), in the presence of a basic substance, and form N-(p-acetamido- or p-aminobenzenesulfonyl)-α-acetylpropionamidine (IIIa or IIIb). In this reaction, basic reagent is required as a condensation agent and the solvent may be water, aliphatic alcohols or ketones, or pyridine, but the condensation does not occur in carbon tetrachloride, benzene, toluene, or ethyl acetate. When the condensation is carried out in a mixed solvent of the one (A) in which the condensation proceeds and the other (B) in which the condensation does not occur, the yield of the condensate differs with the mixing ratio of the solvents and the amount of condensation agent, the yield being good when (A) alone is used and decreases markedly as the amount of (B) increases. Hydrolysis of (III) with acid or alkali affords N-(p-acetamido- or p-aminobenzenesulfonyl) -α-acetylpropionamide (IVa or IVb) and (II) under mild conditions and (II) alone under drastic conditions. (III) forms its semicarbazone (Va or Vb) with semicarbazide hydrochloride and 5-(p-acet-amido- or -amino-benzenesulfonylamido)-3, 4-dimethylpyrazole (VIa or VIb) with hydrazine sulfate.
