Dadiboyena Sureshbabu, Valente Edward J, Hamme Ashton T
Department of Chemistry & Biochemistry, College of Science, Engineering and Technology, Jackson State University, Jackson, Mississippi 39217 USA.
Tetrahedron Lett. 2010 Mar 3;51(9):1341. doi: 10.1016/j.tetlet.2010.01.017.
The syntheses of an important class of hitherto unreported novel pyrazoles are described. The regioselective synthesis of 1,3,4,5-tetrasubstituted pyrazoles was achieved by the Huisgen cyclization of nitrile imines with a trisubstituted bromoalkene. The substituted bromoalkene functions as an alkyne synthon which was used to construct 5,5-disubstituted bromopyrazoline intermediates that undergo aromatization to the analogous pyrazoles through the loss of HBr. The cycloaddition regioselectivity was confirmed through single X-ray crystal data of one of the pyrazoles.
本文描述了一类迄今未报道的重要新型吡唑的合成方法。通过腈亚胺与三取代溴代烯烃的惠斯根环化反应，实现了1,3,4,5-四取代吡唑的区域选择性合成。取代溴代烯烃作为炔烃合成子，用于构建5,5-二取代溴代吡唑啉中间体，该中间体通过失去HBr芳构化为类似的吡唑。通过其中一种吡唑的单晶X射线晶体数据证实了环加成反应的区域选择性。
