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We presented the synthesis of isoindolone spirosuccinimides via the Rh(i)-catalysed reaction of aromatic amides that contain a (2-methylthio)aniline directing group with maleimides. Several possible reaction paths were examined by DFT calculations.

Hydrodefluorination selective to the ortho position to amides is accomplished under mild conditions using sodium borohydride and a nickel catalyst. The facile formation of a nickelacycle intermediate with a specific geometry ensures selectivity without the need for electronic directing groups, and fluorine atoms in other positions remain intact. This method avoids the use of stoichiometric silanes which are typical for most other defluorination reactions, resulting in virtually no organic waste byproducts.

The Rh(i)-catalysed imine-directed oxidative [3 + 2] cycloaddition of benzylamines with maleimides is reported. The reaction is proposed to proceed via a zwitterionic intermediate.

A palladium-catalyzed reaction of N-phthaloyl hydrazones derived from aldehydes and cyclobutanones, leading to the production of nitriles, is described.

This chapter summarizes some selected examples of nickel-catalyzed directed C—H functionalization reactions that involve the activation of a C—H bond as a key step. It is now recognized that nickel complexes, mostly nickel(0) and nickel(II), are some of the most attractive and effective catalysts for the development of C—H functionalization reactions because of the low cost and earth-abundance of nickel, and, most importantly, because the complexes can exist in various oxidation states (+1, +2, +3, and +4) during the transformation, which leads to unique reactivity.

The rhodium(II)-catalyzed, branch-selective C–H alkylation of aryl sulfonamides with vinylsilanes was recently developed by our group, and the unique reactivity and selectivity of the reaction was ...

Nucleophilic aromatic substitution (SNAr) reactions of non-activated aryl fluorides with amide enolates are reported. DFT calculations suggest that the reaction proceeds through a concerted SNAr pathway.

The rhodium(III)-catalyzed oxidative C–H alkenylation and coupling sequence of unprotected 1-naphthylamines with α,β-unsaturated esters, which were recently developed by our group, provide an effic...

The branch-selective C–H alkenylation with alkenes using an iridium catalyst is reported. The Ir(III)-catalyzed reaction of aniline derivatives that contain a pyrimidine-directing group with vinyls...

The ruthenium(II)-catalyzed ortho-C–H arylation of 2-aroyl-imidazoles with aryl bromides and chloride is reported. An imidazole ring functions both as a masked ester and a directing group for C–H a...

Ni-catalyzed cross-electrophile coupling between C(sp2)–F bonds in ortho-fluoro-substituted aromatic amides and C(sp2)–Cl bonds in aryl chlorides in the presence of Zn as a reductant and LiOtBu as ...

Synthesis of 1H-isochromen-1-one derivatives through the C-F/O-H annulation of ortho-fluoro-substituted benzoic acids and alkynes catalyzed by a nickel complex is reported. The reaction involves th...

A new class of dirhodium(II) complexes with tethered sulfonamide and carboxamide ligands was synthesized and characterized. A new type of coordination mode was found for the quinoline moiety containing a sulfonamide ligand, which afforded the axially coordination-free bimetallic dirhodium complexes. Studies were conducted on the catalytic properties of these complexes for cyclopropanation reactions, and the findings indicate that a free axial coordination site is crucial for achieving a high degree of reactivity.

Organoboron reagents are important synthetic intermediates and have wide applications in synthetic organic chemistry. The selective borylation strategies that are currently in use largely rely on t...

Regioselective coupling reaction of N-substituted imidazoles with isocyanates in the presence of a stoichiometric amount of hydrosilanes catalyzed by Ir4(CO)12 to give imidazole-2-carboxamides is reported. Imidazoles bearing an (O-silyl)carboximidate group at the 2-position appear to be initially formed in the reaction; these are then hydrolyzed to the final products in situ. The addition of the hydrosilane was essential for the catalytic reaction to proceed. Substituents on the imidazole ring had no effect on the reaction, except for certain bulky substituents such as t Bu and Ph groups at the 4-position. Triazoles such as 4-methyl-4H-1,2,4-triazole and 1-methyl-1H-1,2,4-triazole were also applicable to this C–H amidation, and the latter reaction proceeded regioselectively at the carbon atom between the sp3 and sp2 nitrogen atoms of the ring, and not between the two sp2 nitrogen atoms.

The Co2(CO)8-catalyzed reaction of acetals with hydrosilanes and CO under mild reaction conditions (an ambient temperature under an ambient CO pressure), leading to the production of vicinal diols ...

The Ni-catalyzed reaction of ortho-phenoxy-substituted aromatic amides with alkynes in the presence of LiOtBu as a base results in C–O/N–H annulation with the formation of 1(2H)-isoquinolinones. The use of a base is essential for the reaction to proceed. The reaction proceeds, even in the absence of a ligand, and under mild reaction conditions (40 °C). An electron-donating group on the aromatic ring facilitates the reaction. The reaction was also applicable to carbamate (C–O bond activation), methylthio (C–S bond activation), and cyano (C–CN bond activation) groups as leaving groups., The Ni-catalyzed reaction of ortho-phenoxy-substituted aromatic amides with alkynes in the presence of LiOtBu as a base results in C–O/N–H annulation with the formation of 1(2H)-isoquinolinones.

Convenient, easily handled, laboratory friendly, robust approaches to afford synthetically important organoboron compounds are currently of great interest to researchers. Among the various available strategies, a metal-free approach would be overwhelmingly accepted, since the target boron compounds can be prepared in a metal-free state. We herein present a detailed study of the metal-free directed ortho-C–H borylation of 2-pyrimidylaniline derivatives. The approach allowed us to synthesize various boronates, which are synthetically important compounds and various four-coordinated triarylborane derivatives, which could be useful in materials science as well as Lewis-acid catalysts. This metal-free directed C–H borylation reaction proceeds smoothly without any interference by external impurities, such as inorganic salts, reactive functionalities, heterocycles and even transition metal precursors, which further enhance its importance.

The palladium-catalyzed 1,1-alkynylbromination of terminal alkenes with a silyl-protected alkynyl bromide is reported. The method tolerates a diverse range of alkenes including vinylarenes, acrylates, and even electronically unbiased alkene derivatives to afford propargylic bromides regioselectively. Mechanistic studies and DFT calculations indicate that the 1,1-alkynylbromination reaction proceeds via the migration of the Pd center followed by the formation of a π-allenyl Pd intermediate, leading to the stereoselective reductive elimination of the C(sp3)–Br bond at the propargylic positon., The first Pd-catalyzed 1,1-alkynylbromination of terminal alkenes using alkynyl bromides, which provides direct access to a variety of functionalized propargylic bromides without the need for an external brominating reagent, is reported.

The efficient Suzuki–Miyaura cross-coupling of ortho-fluoro aromatic secondary amides with aryl boronates is described. The use of KOtBu is essential for the reaction to proceed. The function of the base is to abstract a proton from an amide nitrogen to generate a weak conjugate base, such as an amidate, which functions as a directing group. The reaction proceeds effectively, even at 60 °C. The reaction exhibits a good tolerance for functional groups and a broad scope for aromatic amides.

Considerable advances have been made in the area of C-H functionalization in the last few decades. A number of approaches including both directed and nondirected strategies have been developed thus far. Among the various C-H functionalizations, C-H borylation is of special interest due to the wide applications of organoboron compounds. In this regard, various transition-metal-catalyzed regioselective strategies have been developed. However, the major concern regarding metal-catalyzed C-H borylation procedures is the requirement of a precious metal as well as the contamination by metal precursors in the desired products, which limit the application of this process in large-scale synthesis. Therefore, recent trends have involved the use of transition-metal-free systems. We summarize recent developments in transition-metal-free regioselective C-H borylation. We believe that this Review will help to increase interest in this field and stimulate further progress.

A continuous-flow synthesis of α-amino acid derivatives via a nitrene transfer by the Ir(III)-catalyzed α-C-H amidation of 2-acylimidazoles with dioxazolones is reported.

The reaction of 2-(2-fluoroaryl) N-heteroaromatic compounds, such as benzimidazole and indole derivatives, with internal alkynes in the presence of a catalytic amount of a nickel complex results in C–F/N–H annulation with alkynes. The reaction shows a high functional group compatibility. The presence of a strong base, such as KOBu­ t or LiOBu t , is required for the reaction to proceed.

The Ni-catalyzed reaction of ortho-fluoro-substituted aromatic amides with alkynes results in C-F/N-H annulation to give 1(2H)-isoquinolinones. A key to the success of the reaction is the use of KOtBu or even weak base, such as Cs2CO3. The reaction proceeds in the absence of a ligand and under mild reaction conditions (40-60 °C). DFT calculations suggest that the pathway for this Ni-catalyzed C-F/N-H annulation involves N-H deprotonation, oxidative addition of a C-F bond, migratory insertion of an alkyne, and reductive elimination to form 1(2H)-isoquinolinone derivatives.

The selective, Rh(I)-catalyzed ortho-C-H alkylation of biologically important aryl sulfonamides with maleimides with the aid of an 8-aminoquinoline directing group is reported. The reaction exhibit...

We report the ruthenium-catalyzed cyclization of 1,6-diynes with two molecules of carbon monoxide and water to give a variety of catechols. This reaction likely proceeds through the intermediacy of...

The RhIII -catalyzed, consecutive double C-H oxidative coupling of free 1-naphthylamine and α,β-unsaturated esters through C-H/C-H and C-H/N-H bonds is reported. The one step reaction leads to the formation of biologically important alkylidene-1,2-dihydrobenzo[cd]indoles scaffolds. This efficient process is much more synthetically convenient and useful than others because the starting materials, such as 1-naphthylamine derivatives are readily available and the free amine serves as a directing group.

Summary The activation of ubiquitous C–H bonds has great significance in the field of organic synthesis given that it represents an ideal method for directly producing valuable chemicals from structurally simple compounds. First-row transition metals have recently been recognized as a potential alternative to noble transition metals because of their low cost, unique reactivity profiles, and easy availability. Among these metals, nickel (Ni) catalysts have drawn considerable attention from the scientific community. This review focuses on Ni-catalyzed C–H functionalization reactions of (hetero)arenes, including alkylation, arylation, alkenylation, alkynylation, borylation, and trifluoromethylation by using non-directing group strategies. In addition, mechanistic aspects of Ni-catalyzed C–H functionalization reactions are discussed because this allows possible new insights into catalyst improvement.

An imidazole moiety was introduced as a removal directing group for carboxylic acid derivatives in the Ir(III)-catalyzed alkynylation of C(sp2)–H and C(sp3)–H bonds with various alkynyl bromides, i...