NIS-mediated regioselective addition of allenamides with pyrazoles: synthesis of iodo-substituted allylic pyrazoles

A strategy for the synthesis of iodo-substituted allylic pyrazoles through NIS-mediated regioselective addition of allenamides with pyrazoles is presented. This reaction proceeds rapidly, is scalable up to a gram scale, and tolerates a broad scope of substrates. Moreover, using 1,2,4-triazole as the nucleophile, the corresponding 1,2-addition product was obtained in good yield. Significantly, the products of this reaction, iodo-substituted allylic pyrazoles, could undergo coupling with phenylacetylene under Sonogashira cross-coupling conditions.