The C-H borylation of aromatic substrates has evolved from a stoichiometric curiosity to a valuable methodology for the synthetic chemist. Understandings of regioselective activation and high functional group tolerance have been considerably praised. Most aromatic substituents, such as alkyl, esters, amides, nitriles, amines, protected phenols and others act as steric obstacles for the iridium catalyst to avoid. This avoidance of appending groups can be reversed into a directed borylation with monophosphine ligands. Alternatively, the SiMe2H group elicits an ortho-directing effect via oxidative addition to the metal center. Described herein is the investigation of a new means to direct borylation.The NH(tert-butoxycarbonyl) group is a unique directing group that under standard borylation conditions provides ortho-directed borylation. The NH(t-Boc) group operates by a hydrogen bonding interaction between the N-H and catalyst. This unique effect was examined for a range of aromatic substructures. Introductory attempts at improving selectivity involved increasing N-H acidity and a ligand screen. The obtained borylated anilines are useful precursors to 3,4-dihydroquinolin-2-one heterocycles.
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