Synthesis of 5-(Fluoroalkyl)isoxazole Building Blocks by Regioselective Reactions of Functionalized Halogenoximes
作者:Bohdan A. Chalyk、Kateryna V. Hrebeniuk、Yulia V. Fil、Konstantin S. Gavrilenko、Alexander B. Rozhenko、Bohdan V. Vashchenko、Oleksandr V. Borysov、Angelina V. Biitseva、Pavlo S. Lebed、Iulia Bakanovych、Yurii S. Moroz、Oleksandr O. Grygorenko
DOI:10.1021/acs.joc.9b02264
日期:2019.12.20
halogenoximes and propargylic alcohol. An alternative approach based on nucleophilic substitution in 5-bromomethyl derivatives was found to be more convenient for the preparation of 5-fluoromethylisoxazoles. Reaction of isoxazole-5-carbaldehydes with the Ruppert-Prakash reagent was used for the preparation of (β,β,β-trifluoro-α-hydroxyethyl)isoxazoles. Utility of described approaches was shown by multigram preparation
报道了从官能化的卤代肟开始合成5-氟烷基取代的异恶唑的综合研究。开发了无罐的CF3取代烯烃和带有酯,溴,氯甲基和受保护氨基的卤代肟的无金属[3 + 2]环加成反应,用于制备5-三氟甲基异恶唑。以区域选择性的方式以高达130g的规模以良好或优异的产率获得了目标3,5-二取代的衍生物。通过相应的5-羟甲基或5-甲酰基衍生物的后期脱氧氟化分别合成5-氟甲基-异氟唑和5-二氟甲基异恶唑,然后通过无金属环合肟和炔丙醇来制备5-氟甲基异恶唑。发现在5-溴甲基衍生物中基于亲核取代的替代方法对于制备5-氟甲基异恶唑更方便。将异恶唑-5-甲醛与Ruppert-Prakash试剂的反应用于制备(β,β,β-三氟-α-羟乙基)异恶唑。通过多链制备侧链官能化的单,二和三氟甲基异恶唑,例如,ABT-418和ESI-09的氟化类似物,表明了所描述方法的实用性。