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Synfacts 2011(12): 1292-1292  
DOI: 10.1055/s-0031-1289404
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Copper-Catalyzed One-Pot Synthesis of 5-Sulfonamidopyrazoles

Contributor(s): Victor Snieckus, Johnathan Board
Y. Li, D. Hong, Y. Zhu, P. Lu*, Y. Wang*
Zhejiang University, Hangzhou, P. R. of China
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Publication History

Publication Date:
18 November 2011 (online)

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Significance

Reported is the synthesis of 5-sulfonamidopyrazoles using a one-pot, two-step procedure. The first step is the precedented ­copper-catalyzed reaction of the sulfonyl azide with the alkyne to form ketenimine A, followed by reaction with a hydrazone to form intermediate B. Zinc-mediated cyclization under oxidative conditions afforded the 5-sulfonamidopyrazoles in reasonable yields. A mechanism for the second step of the reaction was proposed, although the only evidence given was the pattern of reactivity of the system.