One-Pot Synthesis of Spirocyclic or Fused Pyrazoles from Cyclic Ketones: Calcium Carbide as the Carbon Source in Ring Expansion
作者:Yue Yu、Yang Chen、Wei Huang、Wanqing Wu、Huanfeng Jiang
DOI:10.1021/acs.joc.7b01496
日期:2017.9.15
N-Tosylhydrazones generated in situ from cyclic ketones smoothly underwent a [3 + 2] cycloaddition to afford saturated spirocyclic pyrazoles and further transformed to the fused analogues via a ring expansion in certain cases. An inexpensive and renewable resource, calcium carbide, was utilized as the carbon source in the ring expansion. The salient features of this reaction include widely available
由环状酮原位生成的N-甲苯磺酰azo平稳地进行[3 + 2]环加成反应,得到饱和的螺环吡唑,并在某些情况下通过扩环进一步转化为稠合类似物。一种廉价且可再生的资源电石用作扩环中的碳源。该反应的显着特征包括广泛可用的起始原料,方便的一锅/两步法,高效率和高区域选择性。值得注意的是,该反应经历了[1,5]-σ重排过程,氘标记实验对此进行了支持。