Cycloaddition of nitrile imines to resin-bound enamines: a solid phase synthesis of 1,4-diarylpyrazoles
作者:Andrew C. Donohue、Sue Pallich、Tom D. McCarthy
DOI:10.1039/b102913b
日期:2001.11.1
The 1,3-dipolar cycloaddition reaction between nitrile imines and resin-bound enamines gives resin-bound pyrazoline intermediates. The piperazine resin functions as a traceless linker and allows these intermediates to be cleaved directly from the resin under mild acid conditions to afford 1,4-diarylpyrazoles. Alternatively they may be chemically modified on the resin prior to elimination from the polymer. The cycloaddition–elimination sequence is regiospecific for the 3,4-disubstituted pyrazole isomer and the products are obtained in good to high yield and in high purity.
氰基亚胺与树脂包埋的不饱和胺之间的1,3-偶极环加成反应生成树脂包埋的吡唑啉中间体。哌嗪树脂作为无痕连接体,允许在温和酸性条件下将这些中间体直接从树脂上切割出来,得到1,4-二芳基吡唑。或者,可以在从聚合物中消除之前对它们进行化学修饰。该环加成-消除序列对3,4-二取代吡唑异构体具有区域特异性,产物的得率良好至高,纯度也很高。