Synthesis of novel pyrazolo[3,4-d]pyridazine, pyrido[1,2-a]benzimidazole, pyrimido[1,2-a]benzimidazole and triazolo[4,3-a]pyrimidine derivatives

✍ Scribed by Mohamed R. Shaaban; Taha M. A. Eldebss; Ahmed F. Darweesh; Ahmad M. Farag

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2008
• Tongue: English
• Weight: 296 KB
• Volume: 45
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570450627

✦ Synopsis

Abstract

magnified image

4‐Acetyl‐5‐methyl‐1‐phenyl‐1__H__‐pyrazole reacts with dimethylformamide dimethylacetal (DMF‐DMA) to afford the corresponding (E)1‐(5‐methyl‐1‐phenyl‐1__H__‐pyrazol‐4‐yl)‐3‐(N,N‐dimethylamino)‐2‐propen‐1‐one. The latter product undergoes regioselective 1,3‐dipolar cycloaddition with nitrilimines and nitrile oxides to afford the novel 3‐aroyl‐4‐(5‐methyl‐1‐phenyl‐1__H__‐pyrazol‐4‐yl)carbonyl‐1‐phenylpyrazole and 3‐aroyl‐4‐(5‐methyl‐1‐phenyl‐1__H__‐pyrazol‐4‐yl)carbonyl isoxazole derivatives, respectively. It reacts also with 1__H__‐benzimidazole‐2‐acetonitrile, 2‐aminobenzimidazole and 3‐amino‐1,2,4‐triazole to afford the novel pyrido[1,2‐a]benzimidazole, pyrimido[1,2‐a]benzimidazole and the triazolo[4,3‐a]pyrimidine derivatives, respectively. The reaction of 3‐aroyl‐4‐(5‐methyl‐1‐phenyl‐1__H__‐pyrazol‐4‐yl) carbonyl‐1‐phenylpyrazole derivatives with hydrazine hydrate led to a new pyrazolo[3,4‐d]pyridazine derivatives.