Highly Regioselective Synthesis of 3,5-Substituted Pyrazoles from Bromovinyl Acetals and N-Tosylhydrazones
作者:Phannarath Phansavath、Virginie Ratovelomanana-Vidal、Anne Westermeyer、Quentin Llopis、Gérard Guillamot
DOI:10.1055/s-0039-1690885
日期:2020.7
pyrazoles was achieved by 1,3-dipolar cycloaddition of diazo compounds, generated in situ from N-tosylhydrazones, with unactivated bromovinyl acetals, which served as alkyne surrogates. The reaction tolerated N-tosylhydrazones bearing various substituted benzylidene groups, and a range of 3,5-disubstituted pyrazoles were obtained in yields of up to 92%.
3,5-二取代吡唑的区域选择性合成是通过重氮化合物的 1,3-偶极环加成实现的,重氮化合物由 N-甲苯磺酰腙原位生成,未活化的溴乙烯基缩醛用作炔烃替代物。该反应耐受带有各种取代亚苄基的 N-甲苯磺酰腙,并且以高达 92% 的产率获得了一系列 3,5-二取代的吡唑。