3-Chloro- and 3-bromo-4-methoxycoumarins 1a,b were readily transformed into 4-halo-5-(2-hydroxyphenyl)-3-oxo-2,3-dihydropyrazoles 2a,b with hydrazines. In the reaction of 1a,b with excess hydrazine and phenylhydrazine in boiling ethanol, unexpected 4-hydrazono-3-(2-hydroxyphenyl)-2-pyrazolin-5-ones 3, 5 were obtained. The structure of 3 was determined by X-ray diffraction analysis.
3-
肼-和3-溴-4-甲氧基
香豆素1a,b易于与
肼转化为4-卤代-5-(2-羟苯基)-3-氧代-2,3-
二氢吡唑2a,b。在的反应1A,B用过量
肼和苯
肼在沸腾的
乙醇,意想不到4-
肼基-3-(2-羟基苯基)-2-
吡唑啉-5-酮3,5获得。通过X射线衍射分析确定3的结构。