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A Simple Phosphine–Diolefin-Promoted Copper-Catalysed N-Arylation of Pyrazoles with (Hetero)aromatic Bromides: The Case of Chloroarenes Revisited

Authors

  • Vincent Rampazzi,

    1. Université de Bourgogne, Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB) UMR-CNRS 6302, 9, avenue Alain Savary 21078 Dijon (France), Fax: (+33) 3-8039-3682
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  • Dr. Alexandre Massard,

    1. Université de Bourgogne, Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB) UMR-CNRS 6302, 9, avenue Alain Savary 21078 Dijon (France), Fax: (+33) 3-8039-3682
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  • Dr. Philippe Richard,

    1. Université de Bourgogne, Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB) UMR-CNRS 6302, 9, avenue Alain Savary 21078 Dijon (France), Fax: (+33) 3-8039-3682
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  • Dr. Michel Picquet,

    1. Université de Bourgogne, Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB) UMR-CNRS 6302, 9, avenue Alain Savary 21078 Dijon (France), Fax: (+33) 3-8039-3682
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  • Prof. Dr. Pierre Le Gendre,

    1. Université de Bourgogne, Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB) UMR-CNRS 6302, 9, avenue Alain Savary 21078 Dijon (France), Fax: (+33) 3-8039-3682
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  • Prof. Dr. Jean-Cyrille Hierso

    Corresponding author
    1. Université de Bourgogne, Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB) UMR-CNRS 6302, 9, avenue Alain Savary 21078 Dijon (France), Fax: (+33) 3-8039-3682
    • Université de Bourgogne, Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB) UMR-CNRS 6302, 9, avenue Alain Savary 21078 Dijon (France), Fax: (+33) 3-8039-3682
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Abstract

A molecularly defined new phosphine–diolefin cubane copper pre-catalyst used at 1.25 mol % under mild conditions promotes the coupling of pyrazoles to functionalised aryl and heteroaryl bromides, which hold a variety of functional groups. This versatile phosphorus-based system was thus successfully used, under identical conditions, for the coupling of a large scope of heteroaromatics to selectively produce pyridinyl- and pyrimidinyl-pyrazoles, as well as several novel furyl-, thienyl- and thiazolyl-substituted pyrazoles. The careful investigation of coupling with the analogous aryl and heteroaryl chlorides clearly indicated that for specifically activated chloroarenes a direct nucleophilic aromatic substitution (SNAr) is easily achieved in the absence of any copper and ligand. These results are pertinent with regards to the reported protocols in which copper–ligand systems have been claimed as useful for coupling activated chloroarenes.

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