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Iridium-catalyzed C–H activation and borylation reactions operate under mild conditions that enable easy and atom-economical installation of the versatile boronate ester group in (het)arenes and alkanes. The standard catalytic system for iridium-catalyzed borylation uses [Ir(cod)(OMe)]2 as a precatalyst, a bipyridine type ligand, and B2 pin2 or HBpin as the borylating agent. Initially, a bipyridine-ligated trisboryl–iridium complex is generated that enables the borylation reaction and the regioselectivity is mainly governed by the sterics of substituents present on the ring. As a result, monosubstituted and 1,2-disubstituted arenes give mixtures of isomers. Significant efforts by several research groups have overcome the selectivity issue for directed proximal C–H borylation by introducing a directing group and newly developed ligands. This short review aims to summarize recent elegant discoveries in directed C(sp2)–H and C(sp3)–H borylation by using heterobidentate ligand (P/N–Si, N–B, and N–C) coordinated iridium catalysts. 1 Introduction 2 Iridium-Catalyzed Directed C–H Borylation of C(sp2)–H Bonds 3 Iridium-Catalyzed Directed C–H Borylation of C(sp3)–H Bonds 4 Conclusions [ABSTRACT FROM AUTHOR]

A method of para‐selective borylation of aromatic amides is described. The borylation proceeded via an unprecedented substrate–ligand distortion between the twisted aromatic amides and a newly designed ligand framework (defa) that is different from the traditionally used ligand (dtbpy) for the C−H borylation reactions. The designed ligand framework (defa) has led to the development of a new type of catalytic system that shows excellent para selectivity for a range of aromatic amides. Moreover, the designed ligand has shown excellent reactivity and selectivity for a range of heterocyclic aromatic amides. The identification of key transition states and intermediates using the DFT computations associated with the three regio‐isomeric pathways revealed that the most efficient catalytic pathway with the defa ligand leads to the para borylation while in the case of bpy the borylation at the para and meta sites compete. [ABSTRACT FROM AUTHOR]

A method of para‐selective borylation of aromatic amides is described. The borylation proceeded via an unprecedented substrate–ligand distortion between the twisted aromatic amides and a newly designed ligand framework (defa) that is different from the traditionally used ligand (dtbpy) for the C−H borylation reactions. The designed ligand framework (defa) has led to the development of a new type of catalytic system that shows excellent para selectivity for a range of aromatic amides. Moreover, the designed ligand has shown excellent reactivity and selectivity for a range of heterocyclic aromatic amides. The identification of key transition states and intermediates using the DFT computations associated with the three regio‐isomeric pathways revealed that the most efficient catalytic pathway with the defa ligand leads to the para borylation while in the case of bpy the borylation at the para and meta sites compete. [ABSTRACT FROM AUTHOR]

Over the past two decades, the C–H bond activation and functionalization reaction has been known as a prevailing method for the construction of carbon–carbon and carbon–heteroatom bonds using various transition metal catalysts. In this context, the iridium-catalyzed C–H bond activation and borylation reaction is one of the most valued methods. However, the major challenge in these borylation reactions is how to control the proximal (ortho) and distal (meta and para) selectivity. Interestingly, while so many approaches are now available for the proximal ortho selective borylation of arenes, borylation at the distal meta and or para position of arenes remains still challenging. Only a few approaches have been reported so far in the literature employing iridium catalysis. In this feature article, we have demonstrated some of the recent discoveries from our laboratories for the proximal (ortho) and distal (meta and para) selective borylation reactions. Moreover, some of the recent catalyst engineering discoveries for the selective proximal ortho borylation reactions for a diverse class of substrates have also been discussed. The discussion part of several other pioneering reports is limited due to the lack of scope of this feature article. [ABSTRACT FROM AUTHOR]

We report a convenient method for the highly site-selective borylation of 8-arylquinoline. The reaction proceeds smoothly in the presence of a catalytic amount of [Ir(OMe)(cod)]2 and 2-phenylpyridine derived ligand using bis(pinacolato)diborane as the borylating agent. The reactions occur with high selectivity with many functional groups, providing a series of borylated 8-aryl quinolines with good to excellent yield and excellent selectivity. The borylated compounds formed in this method can be transformed into various important synthons by using known transformations. [ABSTRACT FROM AUTHOR]

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. L‐Shaped: A new concept for the meta borylation of aromatic amides is described. It has been shown that while esters give para borylations, amides result in meta borylations. For achieving high meta selectivity, an L‐shaped ligand is used and engages in an O⋅⋅⋅K noncovalent interaction with the moderately distorted amide carbonyl group, providing exceptional control for meta C−H activation/borylation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A method of para‐selective borylation of aromatic amides is described. The borylation proceeded via an unprecedented substrate–ligand distortion between the twisted aromatic amides and a newly designed ligand framework (defa) that is different from the traditionally used ligand (dtbpy) for the C−H borylation reactions. The designed ligand framework (defa) has led to the development of a new type of catalytic system that shows excellent para selectivity for a range of aromatic amides. Moreover, the designed ligand has shown excellent reactivity and selectivity for a range of heterocyclic aromatic amides. The identification of key transition states and intermediates using the DFT computations associated with the three regio‐isomeric pathways revealed that the most efficient catalytic pathway with the defa ligand leads to the para borylation while in the case of bpy the borylation at the para and meta sites compete. [ABSTRACT FROM AUTHOR]

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. While controlling the site-selectivity was one of the most challenging issues in these C–H borylation reactions, enormous efforts of several research groups proved instrumental in dealing with selectivity issues that presently reached an impressive level for both proximal and distal C–H bond borylation reactions. For example, in the case of ortho C–H bond borylation reactions, innovative methodologies have been developed either by the modification of the directing groups attached with the substrates or by creating new catalytic systems via the design of new ligand frameworks. Whereas meta and para selective C–H borylations remained a formidable challenge, numerous innovative concepts have been developed within a very short period of time by the development of new catalytic systems with the employment of various noncovalent interactions. Moreover, significant advancements have occurred for aliphatic C(sp3)–H borylations as well as enantioselective borylations. In this review article, we aim to discuss and summarize the different approaches and findings related to the development of directed proximal ortho, distal meta/para, aliphatic (racemic and enantioselective) borylation reactions since 2014. Additionally, considering the C–H borylation reaction as one of the most important mainstream reactions, various applications of this C–H borylation reaction toward the synthesis of natural products, therapeutics, and applications in materials chemistry will be summarized in the last part of this review article. [ABSTRACT FROM AUTHOR]