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  • Hydrogen Bond Directed orth...
    Bai, Shao‐Tao; Bheeter, Charles B.; Reek, Joost N. H.

    Angewandte Chemie (International ed.), September 9, 2019, Volume: 58, Issue: 37
    Journal Article

    Reported is an iridium catalyst for ortho‐selective C−H borylation of challenging secondary aromatic amide substrates, and the regioselectivity is controlled by hydrogen‐bond interactions. The BAIPy‐Ir catalyst forms three hydrogen bonds with the substrate during the crucial activation step, and allows ortho‐C−H borylation with high selectivity. The catalyst displays unprecedented ortho selectivities for a wide variety of substrates that differ in electronic and steric properties, and the catalyst tolerates various functional groups. The regioselective C−H borylation catalyst is readily accessible and converts substrates on gram scale with high selectivity and conversion. Organization is key: Direct ortho‐selective C−H borylation is extremely challenging. Reported here is the first example for direct ortho‐C−H borylation of valuable secondary aromatic amides, and it involves preorganization through hydrogen‐bond formation between the ligand and the amide group of the substrate. The new iridium catalyst is readily available and yields unprecedented regioselectivity for more than 26 substrates without the need for specific directing groups.