Acetylenic ketones. Part VI . Reaction of aroylphenylacetylenes with hydrazine derivatives

The reaction of aroylphenylacetylenes (I) with acyl‐ or aroylhydrazines (II) gave ω‐aroyl‐acetophenone‐ N ‐acyl or N ‐aroylhydrazones (IV). The latter gave upon treatment with methanolic potassium hydroxide and with acetic anhydride in the presence of sodium acetate, the corresponding pyrazoles (V) and the N ‐acetylpyrazoles (VII and VIII), respectively. The acetylenic ketones ( 1 ) also reacted with methylhydrazine and 1,1‐dimethylhydrazine to give 5‐aryl‐1‐methyl‐3‐phenylpyrazoles (XII), and 1,1‐dimethylhydrazine derivatives (XIII), respectively. When the latter compounds were heated with acetic anhydride, they gave the N ‐methylpyrazoles (XII).