Mechanistic Analysis of Iridium(III) Catalyzed Direct C[BOND]H Arylations: A DFT Study

Authors

  • Max García-Melchor,

    1. Centre for Catalysis Research and Innovation (CCRI), Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5 (Canada), Fax: (+1) 613-562-5170
    2. Química Física, Departament de Química, Edifici C.n, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain)
    Search for more papers by this author
  • Prof. Serge I. Gorelsky,

    Corresponding author
    1. Centre for Catalysis Research and Innovation (CCRI), Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5 (Canada), Fax: (+1) 613-562-5170
    • Centre for Catalysis Research and Innovation (CCRI), Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5 (Canada), Fax: (+1) 613-562-5170
    Search for more papers by this author
  • Prof. Tom K. Woo

    Corresponding author
    1. Centre for Catalysis Research and Innovation (CCRI), Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5 (Canada), Fax: (+1) 613-562-5170
    • Centre for Catalysis Research and Innovation (CCRI), Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5 (Canada), Fax: (+1) 613-562-5170
    Search for more papers by this author

Abstract

In a recent experimental work the Ir complex [Ir(cod)(py)(PCy3)](PF6) (that is, Crabtree’s catalyst) has been shown to catalyze the C[BOND]H arylation of electron-rich heteroarenes with iodoarenes using Ag2CO3 as base. For this process, an electrophilic metalation mechanism, (SEAr) has been proposed as operative mechanism rather than the concerted metalation–deprotonation (CMD) mechanism, widely implicated in Pd-catalyzed arylation reactions. Herein we have investigated the C[BOND]H activation step for several (hetero)arenes catalyzed by a IrIII catalyst and compared the data obtained with the results for the PdII-catalyzed C[BOND]H bond activation. The calculations demonstrate that, similar to PdII-catalyzed reactions, the IrIII-catalyzed direct C[BOND]H arylation occurs through the CMD pathway which accounts for the experimentally observed regioselectivity. The transition states for IrIII-catalyzed direct C[BOND]H arylation feature stronger metal–C(arene) interactions than those for PdII-catalyzed C[BOND]H arylation. The calculations also demonstrate that ligands with low trans effect may decrease the activation barrier of the C[BOND]H bond cleavage.

Ancillary