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Transition metal-catalysed direct borylation of hydrocarbons via C–H bond activation has received a remarkable level of attention as a popular reaction in the synthesis of organoboron compounds owing to their synthetic versatility.

A new catalytic method for

A double-fold ortho and remote C-H borylation of BINOL is described. The proposed mechanisms involved electrostatically and sterically directed ortho and remote C-H activation processes, respectively. While B2eg2 (eg = ethylene glycolate) directs the C-H activation at ortho positions, a combination of HBpin and B2pin2 activates remote C-H bonds. The strategy was combined with Suzuki arylation as a one-pot protocol for the rapid synthesis of BINOL derivatives with retention of chirality.

An electrostatically directed meta borylation of sterically biased and unbiased substrates is described. The borylation follows an electrostatic interaction between the partially positive and negative charges between the ligand and substrate. With this strategy, it has been demonstrated that a wide number of challenging substrates, especially 4-substituted substrates, can selectively be borylated at the meta position. Moreover, unsubstituted substrates also displayed excellent meta selectivity. The reaction employs a bench-stable ligand and proceeds at a milder temperature, precluding the need to synthesize a bulky and sophisticated ligand/template.

A new concept for the meta-selective borylation of aromatic amides is described. It has been demonstrated that while esters gave para borylations, amides lead to meta borylations. For achieving high meta selectivity, an L-shaped bifunctional ligand has been employed and engages in an O⋅⋅⋅K noncovalent interaction with the oxygen atom of the moderately distorted amide carbonyl group. This interaction provides exceptional control for meta C-H activation/borylation.

High ortho selectivity for Ir-catalyzed C–H borylations (CHBs) of anilines results when B2eg2 (eg = ethylene glycolate) is used as the borylating reagent in lieu of B2pin2, which is known to give isomeric mixtures with anilines lacking a blocking group at the 4-position. With this modification, high selectivities and good yields are now possible for various anilines, including those with groups at the 2- and 3-positions. Experiments indicate that ArylN(H)Beg species are generated prior to CHB and support the improved ortho selectivity relative to B2pin2 reactions arising from smaller Beg ligands on the Ir catalyst. The lowest-energy transition states (TSs) from density functional theory computational analyses have N–H···O hydrogen-bonding interactions between PhN(H)Beg and O atoms in Beg ligands. Ir-catalyzed CHB of PhN(H)Me with B2eg2 is also highly ortho-selective. 1H NMR experiments show that N-borylation fully generates PhN(Me)Beg prior to CHB. The TS with the lowest Gibbs energy was the ortho TS, in which the Beg unit is oriented anti to the bipyridine ligand.

Noncovalent interactions play a fundamental role in molecular biology, crystal engineering, supramolecular chemistry, drug design, sensing applications, and many other research fields in the chemical sciences. Because of this importance, thorough research efforts have been focused on the interpreting and quantifying these interactions, which include H-bonding, electrostatic effects, π π interaction, cation-π interaction, hydrophobic-hydrophobic interaction, van der Waals forces, and other such type of interactions. However, on the synthetic standpoint, use of these noncovalent interactions are rare, although might be beneficial for the site-selective C H bond activation and functionalization by transition metal catalysis. In this context, iridium-catalyzed C H borylation has gained immense popularity due to the versatility conferred to the C B bonds. Very recently, researchers have started employing these interactions as a governing factor for attaining regioselectivity in arene C H borylation. In this perspective, we will focus on the advancements made so far by the use of various noncovalent interactions in Ir-catalyzed borylations.

An efficient strategy for the para-selective borylation of aromatic esters is described. For achieving high para-selectivity, a new catalytic system has been developed modifying the core structure of the bipyridine. It has been proposed that the L-shaped ligand is essential to recognize the functionality of the oxygen atom of the ester carbonyl group via noncovalent interaction, which provides an unprecedented controlling factor for para-selective C-H activation/borylation.

A ligand-controlled discovery of ortho and meta C–H boryl­ation of aromatic aldehydes is described. In both cases, an amine is used and it was proposed that ortho borylation could be realized using tert-butylamine as the traceless protecting/directing group and meta boryl­ation undergoes via an electrostatic interaction and a secondary interaction between the ligand of the iridium catalyst and the substrate. Remarkably, these electrostatic interactions and secondary B–N interactions offer a unique and unprecedented guiding factor for the meta-selective C–H activation/borylation of benzaldehydes. This is the first example for the C–H activation and functionalization where the ortho and meta position of a substrate has selectively been functionalized, which open a new chapter in electrophilic aromatic substitution chemistry. 1 Introduction 2 C–H Activation and ortho Borylation of Benzaldehydes 3 C–H Activation and meta Borylation of Benzaldehydes 4 Conclusion

The ligand-enabled development of ortho and meta C-H borylation of aromatic aldehydes is reported. It was envisaged that while ortho borylation could be achieved using tert-butylamine as the traceless protecting/directing group, meta borylation proceeds via an electrostatic interaction and a secondary interaction between the ligand of the catalyst and the substrate. These ligand-substrate electrostatic interactions and secondary B-N interactions provide an unprecedented controlling factor for meta-selective C-H activation/borylation.

The ligand-enabled development of ortho and meta C–H borylation of aromatic aldehydes is reported. It was envisaged that while ortho borylation could be achieved using tert-butylamine as the traceless protecting/directing group, meta borylation proceeds via an electrostatic interaction and a secondary interaction between the ligand of the catalyst and the substrate. These ligand–substrate electrostatic interactions and secondary B–N interactions provide an unprecedented controlling factor for meta-selective C–H activation/borylation.