Copper- or Thermally Induced Divergent Outcomes: Synthesis of 4-Methyl 2<i>H</i>
-Chromenes and Spiro-4<i>H</i>
-Pyrazoles
作者:Yang Zheng、Lihua Qiu、Kemiao Hong、Shanliang Dong、Xinfang Xu
DOI:10.1002/chem.201704759
日期:2018.5.7
transformation of alkyne tethered N‐sulfonyl hydrazones is reported, which provides a direct and effective access to 4‐methyl 2H‐chromene derivatives and spiro‐4H‐pyrazoles in the presence of copper catalyst or under thermal conditions, respectively. The notable features of this process include readily available starting materials, an inexpensive copper catalyst, mild reaction conditions, broad substrate scope
据报道,炔烃连接的N-磺酰基具有前所未有的不同结果转化,在铜催化剂存在下或在热条件下,这分别提供了直接和有效地获得4-甲基2 H-色烯衍生物和spiro-4 H-吡唑的途径。。该方法的显着特征包括容易获得的起始原料,廉价的铜催化剂,温和的反应条件,广泛的底物范围,这些生成的产物的各种转化和潜在应用。机理研究表明3 H通过直接[3 + 2]环加成反应生成的吡唑是这两种不同转化的公共关键中间体。据我们所知,这是磺化反应唯一经历级联过程的例子,该过程涉及3 H-吡唑,这是首次通过单晶X射线衍射分析分离并确认。