Palladium-catalysed direct arylations of NH-free pyrrole and N-tosylpyrrole with aryl bromides

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• 作者：Charles Beromeo Bheeter^a ; Jitendra K. Bera^b ; Henri Doucet^a ; ^{henri.doucet@univ-rennes1.fr}
• 关键词：Pyrroles ; Aryl bromides ; C&ndash ; H activation ; Catalysis ; Palladium
• 刊名：Tetrahedron Letters
• 出版年：2012
• 出版时间：1 February, 2012
• 年：2012
• 卷：53
• 期：5
• 页码：509-513
• 全文大小：1456 K

文摘

The palladium-catalysed direct coupling of aryl halides with pyrroles provides a greener access to arylated pyrroles than more classical couplings such as Suzuki, Stille or Negishi reactions. However, so far, m>Nm>H-free pyrrole and m>Nm>-tosylpyrrole gave disappointing results for such couplings either in terms of regioselectivity of the arylation, catalyst loading or substrate scope. The reactivity of both m>Nm>H-free pyrrole and m>Nm>-tosylpyrrole was studied, and the tosylated pyrrole led to higher yields of coupling products due to better conversions of the aryl bromides. A range of aryl bromides undergo regioselective coupling at C2 of m>Nm>-tosylpyrrole in moderate to good yields using 1 mol  % [Pd(Cl(C₃H₅)]₂ as the catalyst, KOAc as the base in DMAc.