Para C–H borylations (CHB) of tetraalkylammonium sulfates and sulfamates have been achieved using bipyridine-ligated Ir boryl catalysts. Selectivities can be modulated by both the length of the alkyl groups in the tetraalkylammonium cations and the substituents on the bipyridine ligands. Ion pairing, where the alkyl groups of the cation shield the meta C–H bonds in the counteranions, is proposed to account for para selectivity. The 4,4′-dimethoxy-2,2′-bipyridine ligand gave superior selectivities.

Regioselectivities in catalytic C−H borylations (CHBs) have been rationalized using simplistic steric models and correlations with nuclear magnetic resonance (NMR) chemical shifts. However, regioselectivity can be significant for important substrate classes where none would be expected from these arguments. In this study, intramolecular hydrogen bonding (IMHB) can lead to steric shielding effects that can direct Ircatalyzed CHB regiochemistry. Bpin (Bpin = pinacol boronic ester)/arene IMHB can promote remote borylations of Nborylated anilines, 2-amino-N-alkylpyridine, tetrahydroquinolines, indoles, and 1-borylated naphthalenes. Experimental and computational studies support molecular geometries with the Bpin orientation controlled by a C−H•••O IMHB. IMHB-directed remote CHB appeared operative in the C6 borylation of 3-aminoindazole (seven-membered IMHB) and C6 borylation of an osimertinib analogue where a pyrimidine IMHB creates the steric shield. This study informs researchers to evaluate not only interbut also intramolecular noncovalent interactions as potential drivers of remote CHB regioselectivity.