3-Ethoxyisoxazoles and 3-ethoxy-1H-pyrazoles were obtained in high yields from β-oxo thionoesters. The reaction of the ethyl β-oxo thionoesters with hydroxylamine hydrochloride in the presence of triethylamine at room temperature for 2 h gave the ethyl 3-oxopropiohydroximates and their hemiacetals, which were easily converted to the 3-ethoxyisoxazoles by refluxing for 3 h at pH 3—5. On the other hand, the reaction of the ethyl β-oxo thionoesters with hydrazine derivatives in the presence of triethylamine for 3—8 h at room temperature directly yielded the 3-ethoxy-1H-pyrazoles.
从β-
噻吩酯中以高产率得到了3-乙氧基
异噁唑和3-乙氧基-1H-
吡唑。在室温下,将乙基β-
噻吩酯与
盐酸羟胺在
三乙胺存在下反应2小时,得到乙基3-氧代丙基
羟胺和它们的
半缩醛,这些产物可以通过在pH 3—5下回流3小时轻松转化为3-乙氧基
异噁唑。另一方面,将乙基β-
噻吩酯与
肼衍
生物在
三乙胺存在下在室温下反应3—8小时,可以直接得到3-乙氧基-1H-
吡唑。