An unusual thionyl chloride-promoted C−C bond formation to obtain 4,4'-bipyrazolones
作者:Gernot A Eller、Gytė Vilkauskaitė、Algirdas Šačkus、Vytas Martynaitis、Ashenafi Damtew Mamuye、Vittorio Pace、Wolfgang Holzer
DOI:10.3762/bjoc.14.110
日期:——
transformed into the corresponding 4,4'-bipyrazoles via alkaline hydrolysis and subsequent decarboxylation. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a representative 5,5'-dioxo-4,4'-bipyrazole-4,4'-dicarboxylate was confirmed by X-ray crystal structure analysis.
通过使5-羟基吡唑-4-羧酸酯在回流的亚硫酰氯中反应,可容易地获得5,5'-二氧代-4,4'-联吡唑-4,4'-二羧酸二烷基酯。所获得的二酯可以通过碱水解和随后的脱羧反应转化为相应的4,4′-联吡唑。对所有制备的产物进行了详细的NMR光谱研究(1H,13C,15N)。此外,通过X射线晶体结构分析确认了代表性的5,5'-二氧代-4,4'-联吡唑-4,4'-二羧酸酯的结构。