A facile two-step procedure for the synthesis of 6-(trifluoromethyl)-1,4,5,6-tetrahydropyrazolo[3,4-b]pyran derivatives (4) from the reaction of 4-arylidene-3-methyl-1-phenyl-5-pyrazolones (1) with ethyl trifluoroacetoacetate (2), a versatile fluorinated building-block, was presented. Furthermore, to increase the efficiency of this reaction, the more convenient one-pot three-component process was also developed with a slightly lower yield. Treatment of 4 with P₂O₅, conc. H₂SO₄, POCl₃/Py or p-TsOH under the drastic conditions did not afford the corresponding dehydrated products.

中文翻译：

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区域选择性合成6-三氟甲基-1,4,5,6-四氢吡唑并[3,4- b ]吡喃衍生物

从4-亚芳基-3-甲基-1的反应合成6-（三氟甲基）-1,4,5,6-四氢吡唑并[3,4- b ]吡喃衍生物（4）的简便两步程序提出了具有多功能氟代砌块的三氟乙酰乙酸乙酯（2）的-苯基-5-吡唑啉酮（1）。此外，为了提高该反应的效率，还开发了一种更方便的单锅三组分方法，其收率略低。用P ₂ O ₅处理4，浓缩。H ₂ SO ₄，POCl ₃ / Py或p在剧烈条件下的-TsOH没有得到相应的脱水产物。