Palladium-Catalysed Regioselective Direct Arylations of Heteroarenes by Bromobenzamides: Direct Synthesis of Heteroaryl Benzamides

Authors

  • Lu Chen,

    1. Institut des Sciences Chimiques de Rennes, UMR 6226, CNRS-Université de Rennes 1, “Organométalliques: Matériaux et Catalyse”, Campus de Beaulieu, 35042 Rennes (France), Fax: (+33) 0223236939
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  • Dr. Christian Bruneau,

    1. Institut des Sciences Chimiques de Rennes, UMR 6226, CNRS-Université de Rennes 1, “Organométalliques: Matériaux et Catalyse”, Campus de Beaulieu, 35042 Rennes (France), Fax: (+33) 0223236939
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  • Prof. Pierre H. Dixneuf,

    1. Institut des Sciences Chimiques de Rennes, UMR 6226, CNRS-Université de Rennes 1, “Organométalliques: Matériaux et Catalyse”, Campus de Beaulieu, 35042 Rennes (France), Fax: (+33) 0223236939
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  • Dr. Henri Doucet

    Corresponding author
    1. Institut des Sciences Chimiques de Rennes, UMR 6226, CNRS-Université de Rennes 1, “Organométalliques: Matériaux et Catalyse”, Campus de Beaulieu, 35042 Rennes (France), Fax: (+33) 0223236939
    • Institut des Sciences Chimiques de Rennes, UMR 6226, CNRS-Université de Rennes 1, “Organométalliques: Matériaux et Catalyse”, Campus de Beaulieu, 35042 Rennes (France), Fax: (+33) 0223236939

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Abstract

The Pd-catalysed direct arylation of heteroarene C[BOND]H bonds by 2- or 4-bromobenzamides has been achieved. In the presence of KOAc as the base, no C[BOND]N bond formation or C[BOND]C coupling of two bromobenzamides was observed. Both primary and tertiary amides can be employed for C[BOND]C cross-coupling of 4-bromobenzamides with a variety of heteroarenes to give the C5-arylated heteroarenes in good yields by using a low loading (0.5 mol %) of Pd(OAc)2 catalyst. However, no coupling product was observed with 2-bromobenzamide, and a moderate reactivity of 2-bromo-N,N-diethylbenzamide has been observed with 2 mol % PdCl(C3H5)(dppb) (dppb=1,4-bis(diphenylphosphino)butane) as the catalyst. A moderate influence due to the nature of the heteroarene was observed, and thiazoles, thiophenes, furans and pyrroles have been arylated successfully. The reaction of a thiazole with 2-bromo-N-phenylbenzamide led to a six-membered ring product by intramolecular cyclisation, whereas a 2-bromo-N-benzylbenzamide gave the desired intermolecular coupling product.

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