Xu Hui, Hong Ran, Weng Ming-Yue, Huang Rong-Lu, Wang Guan-Wu, Zhang Ze
Anhui Province Key Laboratory of Functional Coordinated Complexes for Materials Chemistry Application and School of Chemical and Environmental Engineering, Anhui Polytechnic University, Wuhu 241000, P. R. China.
CAS Key Laboratory of Soft Matter Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China.
Org Lett. 2021 Jul 16;23(14):5305-5310. doi: 10.1021/acs.orglett.1c01475. Epub 2021 Jul 2.
The solvent-free reaction of 4-alkylidene pyrazolones with amidines can furnish 4,5'-imidazolinyl spiropyrazolones in good to excellent yields when promoted by -iodosuccinimide under solvent-free ball-milling conditions, whereas it almost exclusively affords 4,4'-imidazolinyl spiropyrazolones if mediated by -bromosuccinimide in heated toluene. On the basis of this switchable cyclization strategy, a powerful metal-free method for regioselective and diastereoselective synthesis of structurally diverse 4,5'- and 4,4'-imidazolinyl spiropyrazolones has been successfully developed.
在无溶剂球磨条件下，由N-碘代琥珀酰亚胺促进时，4-亚烷基吡唑啉酮与脒的无溶剂反应能够以良好至优异的产率提供4,5'-咪唑啉基螺吡唑啉酮；而在加热的甲苯中由N-溴代琥珀酰亚胺介导时，该反应几乎专一性地生成4,4'-咪唑啉基螺吡唑啉酮。基于这种可切换的环化策略，已成功开发出一种强大的无金属方法，用于区域选择性和非对映选择性合成结构多样的4,5'-和4,4'-咪唑啉基螺吡唑啉酮。
