Synthesis of Difluoromethylated Pyrazoles by the [3 + 2] Cycloaddition Reaction of Difluoroacetohydrazonoyl Bromides

作者：Tongyu Han, Ke‐Hu Wang, Ming Yang, Pengfei Zhao, Feng Wang, Junjiao Wang, Danfeng Huang, Yulai Hu · 发表于：The Journal of Organic Chemistry · 年份：2021 · DOI：10.1021/acs.joc.1c02521 · 被引用次数：44 · 研究领域：Fluorine in Organic Chemistry、Synthesis and Reactions of Organic Compounds、Cyclopropane Reaction Mechanisms

As novel and efficient difluoromethyl building blocks, difluoroacetohydrazonoyl bromides have been synthesized for the first time. The synthetic utility of this reagent for the construction of difluoromethyl organic compounds is demonstrated by their effective regioselective [3 + 2] cycloaddition reactions with ynones, alkynoates, and ynamides. The reactions provide a novel and efficient protocol to access difluoromethyl-substituted pyrazoles in good to excellent yields.