Dadiboyena Sureshbabu, Hamme Ashton T
Department of Chemistry & Biochemistry, College of Science, Engineering and Technology, Jackson State University, Jackson, Mississippi 39217 USA.
Tetrahedron Lett. 2011 May 18;52(20):2536-2539. doi: 10.1016/j.tetlet.2011.03.004.
Regioisomeric spiropyrazolines were synthesized through a tandem intramolecular cyclization/methylation reaction of a functionalized 5,5-disubstituted pyrazoline in one reaction vessel. The 5,5-pyrazolines were constructed through a 1,3-dipolar cycloaddition reaction of aromatic ring containing nitrile imines and a disubstituted geminal alkene. An evaluation of the relative location of the nucleophilic and electrophilic functional groups on the pyrazoline was performed in order to ascertain the best pyrazoline system for the intramolecular cyclization/methylation reaction. Higher spiropyrazoline isolated yields were realized from pyrazolines with the electrophilic ester located further away from the pyrazoline when compared to pyrazolines with a directly bonded ester.
通过在一个反应容器中使功能化的5,5-二取代吡唑啉进行串联分子内环化/甲基化反应，合成了区域异构体螺吡唑啉。5,5-吡唑啉是通过含腈亚胺的芳香环与二取代偕二烯烃的1,3-偶极环加成反应构建的。对吡唑啉上亲核和亲电官能团的相对位置进行了评估，以确定用于分子内环化/甲基化反应的最佳吡唑啉体系。与具有直接键合酯的吡唑啉相比，亲电酯离吡唑啉更远的吡唑啉实现了更高的螺吡唑啉分离产率。
