Generation and cycloaddition of polymer-supported azomethine imines: traceless synthesis of pyrazole derivatives from α-silylnitrosoamide derivatives bound to resin

1,3-Dipolar cycloaddition of polymer-supported azomethine imines with dimethyl acetylenedicarboxylate (DMAD) gave pyrazole derivatives in good yields. The azomethine imines were generated from polymer-supported α-silylnitrosoamides by a 1,4-silatropic shift. The feature of this reaction is that no cleavage operations are required after the cycloaddition.