N. A. Shams

NOVEL METHODS FOR THE SYNTHESIS OF SOME PYRIDAZINO-, FURO-, AND POLYSUBSTITUTED PYRIDAZINES

ABSTRACT 3,4-Diethoxycarbonyl-5,6-diphenylpyridazine 1 reacted with hydrazine hydrate to form tetrahydropyridazino [4,5-c]pyridazine 2, which reacted with ethyl bromoacetate to give 6,7-diethoxycarbonylmethyl-3,4-diphenyl-5,8-dioxopyridazino [4,5-c]pyridazine 3. However, acetylation of 2 with acetyl chloride gave three different pyridazino[4,5-c]pyridazines 4–6. The reaction of the starting diester 1 with different amounts of phenylmagnesium bromide gave different products 7–10. The structure of product 8 was elucidated by alkaline hydrolysis and hydrazinolysis to afford 11 and 13, respectively. Treatment of 13 with benzaldehyde in piperidine yielded the starting Grignard product 8 and benzalazine 17.

Synthesis and reactions of 3,4-dicarboxy-5,6-diphenylpyridazine

Abstract Diethyl acetylenedicarboxylate 2 reacted with benzilmonohydrazone 1 to form 3,4-dicarboxycarbony 1-5,6-diphenylpyridazine 3, which upon alkaline hydrolysis gave the corresponding dicarboxylic acid 4. Decarboxylation of 4 gave 3,4-diphenyl-pyridazine 7. On treatment of 4 with acetyl chloride or thionyl chloride, 3,4-diphenyl-5,7-dioxofuro[3,4-c]pyridazine 8 was formed. Friedel-Crafts acylation on 8 gave 4-benzoyl-3-carboxy-5,6-diphenylpyridazine 9, 3-benzoyl-4-carboxy-5,6-diphenyl-pyridazine 10 and 4-benzoyl-5,6-diphenylpyridazine 11. Hydrazinolyis of 9 and 10 produced the isomeric pyridazino[4,5-]pyridazines 15 and 16, respectively. Reaction of 5,7-di-oxofuro[3.4-c]pyridazine 8 with distilled aniline gave the unexpected product 3,4-diphenyl-5-(N-phenyl) formamidopyridazine 17.