The synthesis of previously unattainable 2,5-disubstituted 4,5-dihydroimidazo[1,5-b]pyrazol-6-ones has been developed. Electrochemical reductions of readily available 2,2,2-trichloroethylideneacetophenones were followed by reaction with hydrazine, leading to 3-aryl-5-dichloromethyl-2-pyrazolines. These were treated with isocyanates to obtain the corresponding aminocarbonyl derivatives, which were found to be able to form an otherwise almost inaccessible imidazo[1,5-b]pyrazole ring system via a one-step reaction involving internal condensation followed by hydrogen chloride elimination and aromatization. The molecular­ structures of 2-(4-methylphenyl)-5-tosyl-4,5-dihydro­imidazo[1,5-b]pyrazol-6-one, 5-dichloromethyl-N-(4-chlorophenyl)-4,5-dihydro-3-p-tolylpyrazole-1-carboxamide, and 5-(4-bromophenyl)-2-p-tolyl-4,5-dihydroimidazo[1,5-b]pyrazol-6-one were determined by X-ray crystallographic analysis.

已经开发了以前无法获得的2，5-二取代的4，5-二氢咪唑并[1，5 - b ]吡唑-6-酮的合成。电化学还原易得的2,2,2-三氯亚乙基苯乙酮，然后与肼反应，生成3-芳基-5-二氯甲基-2-吡唑啉。将它们用异氰酸酯处理以获得相应的氨基羰基衍生物，发现它们能够通过一步反应（包括内部缩合，然后去除氯化氢和氢键）形成咪唑并[1,5- b ]吡唑环系统。芳香化。2-（4-甲基苯基）-5-甲苯基-4,5-二氢咪唑并[1,5 - b ]吡唑-6-，5-二氯甲基-N的分子结构-（4-氯苯基）-4,5-二氢-3-对甲苯基吡唑-1-羧酰胺和5-（4-溴苯基）-2-对甲苯基-4,5-二氢咪唑[1,5- b ]通过X射线晶体学分析确定吡唑-6-一。