The invention discloses a novel process for the preparation of a compound of formula II
wherein
R₁is C₁₋₅alkyl,
R₂is hydrogen or C₁₋₅alkyl, and
R₃is optionally substituted phenyl,
comprising the reaction of a 4-hydroxypyrazole of formula III
wherein R₁ and R₂ are as defined for formula II, with a benzylhalide of formula IV
Hal-CH₂-R₃ (IV)
wherein Hal is halogen, preferably bromine or chlorine, and R₃ is as defined for formula II, in the presence of a base. The invention further comprises a novel process for the preparation of the 4-hydroxypyrazole of formula III. The compounds of formulae II and III are intermediates for highly effective systemic fungicides of the class of pyrazolyl acetic acid derivatives.
本发明公开了一种制备式 II 化合物的新工艺
式中
R₁ 是 C₁₋₅ 烷基、
R₂ 是氢或 C₁₋₅ 烷基,以及
R₃ 是任选取代的苯基、
包括式 III 的
4-羟基吡唑的反应
其中 R₁ 和 R₂ 如式 II 所定义,与式 IV 的苄基卤化物反应
Hal-CH₂-R₃ (IV)
其中 Hal 是卤素,最好是
溴或
氯,R₃ 如式 II 所定义,在碱存在下。本发明还包括一种制备式 III 的
4-羟基吡唑的新工艺。式 II 和 III 的化合物是
吡唑乙酸衍
生物类高效内吸性杀菌剂的中间体。