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.