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Issue 24, 1999
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Peculiarities of copper(I)- and palladium-catalyzed cross-coupling of terminal alkynes with vicinal amino- and (N-acetylamino)-iodopyrazoles. Synthesis of alkynylaminopyrazoles

Abstract

A number of vicinal amino- and (N-acetylamino)-alkylpyrazoles have been synthesized by cross-coupling reactions of iodopyrazoles with alk-1-ynes using a combination of Pd(PPh3)2Cl2 and CuI as catalyst in Et3N or with copper acetylides. The latter Stephens–Castro reaction of copper acetylides with these amino- and (N-acetylamino)-iodopyrazoles was established as a common method for the preparation of (N-acetylamino)alkynylpyrazoles. The Pd/Cu-catalyzed cross-coupling of iodopyrazoles (Sonogashira reaction) with alk-1-ynes bearing electron-releasing substituents was unsuitable for the synthesis of alkynylpyrazoles: 3- and 5-iodopyrazoles were unreactive but, in the case of 4-iodo derivatives, reductive deiodination, accompanied by homocoupling of the alk-1-yne component, was the only reaction.

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Article type: Paper
DOI: 10.1039/A903754C
Citation: J. Chem. Soc., Perkin Trans. 1, 1999,0, 3713-3720

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    Peculiarities of copper(I)- and palladium-catalyzed cross-coupling of terminal alkynes with vicinal amino- and (N-acetylamino)-iodopyrazoles. Synthesis of alkynylaminopyrazoles

    E. V. Tretyakov, D. W. Knight and S. F. Vasilevsky, J. Chem. Soc., Perkin Trans. 1, 1999, 0, 3713
    DOI: 10.1039/A903754C

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