Regioselective One-Step Synthesis of Pyrazoles from Alkynes and N-Tosylhydrazones: [3+2] Dipolar Cycloaddition/[1,5] Sigmatropic Rearrangement Cascade
作者:M. Carmen Pérez-Aguilar、Carlos Valdés
DOI:10.1002/anie.201301284
日期:2013.7.8
Rearrangement under control: A wide variety of 3,4,5‐ and 1,3,5‐trisubstituted pyrazoles can be prepared from tosylhydrazones of ketones and terminal alkynes through the title reaction sequence (see scheme; Ts=4‐toluenesulfonyl). The rearrangement, and therefore, the regioselectivity of the reaction is controlled by the nature of the substituents of the tosylhydrazone.
在控制下进行重排:可以通过标题反应顺序(参见方案; Ts = 4-甲苯磺酰基),从酮和末端炔烃的甲苯磺酰prepared制备各种各样的3,4,5-和1,3,5-三取代的吡唑。反应的重排以及因此的区域选择性由甲苯磺酰hydr的取代基的性质控制。