Formyl Substituent at C??4 of Pyrazoles: A Temporary Protecting Group for Regioselective Palladium??Catalyzed Direct Arylation at C??5

I Smari, C Youssef, K Yuan, A Beladhria…

Index: Smari, Imen; Youssef, Chiraz; Yuan, Kedong; Beladhria, Anissa; Ben Ammar, Hamed; Ben Hassine, Bechir; Doucet, Henri European Journal of Organic Chemistry, 2014 , vol. 2014, # 8 p. 1778 - 1786

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Abstract

Abstract Pyrazoles with an aldehyde function at C-4 underwent a palladium-catalyzed direct arylation reaction to provide a regioselective approach to 5-aryl-substituted pyrazoles. The reaction proceeds in moderate to high yields with a variety of aryl bromides in the presence of 2 mol-% of Pd (OAc) 2 as the catalyst. The use of an aldehyde function at C-4 of the pyrazoles presents several advantages:(1) 4-formylpyrazoles are easily prepared from ...

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