Weinreb Amide Directed Versatile C-H Bond Functionalization under (η5 -Pentamethylcyclopentadienyl)cobalt(III) Catalysis

The (η⁵ -pentamethylcyclopentadienyl)cobalt(III) (Cp*Co^III )-catalyzed C-H bond functionalization of aromatic, heteroaromatic, and α,β-unsaturated Weinreb amides was explored. C-H allylation reactions with the use of allyl carbonate and a perfluoroalkene, oxidative alkenylation reactions with the use of ethyl acrylate, iodination reactions with the use of N-iodosuccinimide, and amidation reactions with the use of dioxazolones were catalyzed by Cp*Co(CO)I₂ in the presence of a cationic Ag salt and AgOAc to afford various synthetically useful building blocks. Mechanistic studies of the C-H allylation disclosed that the C-H activation step was rate determining and virtually irreversible.

Ru(II)-Catalyzed C-H Aminocarbonylation of N-(Hetero)aryl-7-azaindoles with Isocyanates

The ruthenium(II)-catalyzed C-H aminocarbonylation of N-(hetero)aryl-7-azaindoles with isocyanates is described. The excellent site selectivity at the ortho-position within the N-(hetero)aryl ring was observed to provide ortho-amidated N-(hetero)aryl-7-azaindoles under the mild reaction conditions. The resulting 7-azaindole derivatives can be readily transformed into 7-azaindoles containing carboxylic acid and alkyl amine functional groups.

Synthesis of TMPA Derivatives through Sequential Ir(III)-Catalyzed C-H Alkylation and Their Antidiabetic Evaluation

The synthesis and antidiabetic evaluation of ethyl 2-[2,3,4-trimethoxy-6-(1-octanoyl)phenyl]acetate (TMPA) and its structural analogs are described. The construction of TMPA derivatives has been successfully achieved in only two steps, which involve the iridium(III)-catalyzed α-alkylation of acetophenones with alcohols and the ketone-directed iridium(III)- or rhodium(III)-catalyzed redox-neutral C-H alkylation of α-alkylated acetophenones using Meldrum's diazo compounds. This synthetic protocol efficiently provides a range of TMPA derivatives with site selectivity and functional group compatibility. In addition, the site-selective demethylation of TMPA derivative affords the naturally occurring phomopsin C in good yield. Moreover, all synthetic compounds were screened for in vitro adenosine 5'-monophosphate-activated protein kinase (AMPK) activation using HepG2 cells. Furthermore, TMPA (5ac) and 5cd showing the most potent AMPK activation were treated for the in vivo antidiabetic experiment. Notably, our synthetic compound 5cd was found to display the powerful antidiabetic effect, stronger than that of metformin and TMPA (5ac).

Transition metal-catalyzed C-H bond functionalization in multicomponent reactions: a tool toward molecular diversity

Transition metal-catalyzed C-H bond functionalization has numerous applications in organic synthesis as a powerful type of bond transformation. In particular, the combination of C-H functionalization with other types of chemical transformations in the manner of multicomponent reactions is an even more beneficial tool in the synthesis of small organic molecules because such reactions provide a platform for the rapid generation of high molecular diversity and complexity by making use of the advantages of both latent C-H bond transformation and the multicomponent reaction. Herein, we provide a review highlighting the research advances in the multicomponent reactions built upon transition metal-catalyzed C-H bond functionalization. The content spans from the reactions featuring the functionalization of C(sp³)-H, C(sp²)-H and C(sp)-H bonds over the last decade.

Synthesis of 2-aminobenzophenones through acylation of anilines with α-oxocarboxylic acids assisted by tert-butyl nitrite

A highly facile all-in-one-pot synthesis of 2-aminobenzophenones directly from anilines, tert-butyl nitrite and α-oxocarboxylic acids under the catalysis of Pd(OAc)₂ is presented.

Copper-catalyzed oxidative functionalization of benzylic C–H bonds with quinazoline 3-oxides

A highly efficient copper-catalyzed oxidative functionalization of benzylic C(sp³)–H bonds with quinazoline 3-oxides has been developed.

Facile synthesis of unnatural β-germyl-α-amino amides via Pd(ii)-catalyzed primary and secondary C(sp3)–H bond germylation

Pd(ii)-Catalyzed direct C(sp³)–H germylation of α-AA derivatives with the assistance of a bidentate auxiliary for the efficient synthesis of β-germyl-α-amino amides is reported.

A new class of N-doped ionic PAHsviaintramolecular [4+2]-cycloaddition between arylpyridines and alkynes

Reported herein, for the first time, is a copper-promoted intramolecular [4+2]-cycloaddition cascade to access ionic N-doped polycyclic aromatic hydrocarbons (PAHs) with tunable emission wavelengths.

Copper-catalyzed α-C–H amidation of simple ethers through C(sp3)–H/N–H cross dehydrogenative coupling

An efficient copper-catalyzed α-C–H amidation of simple ethers with N-(8-quinolyl)amides through C(sp³)–H/N–H cross dehydrogenative coupling was developed.

Ag1 Pd1 Nanoparticles-Reduced Graphene Oxide as a Highly Efficient and Recyclable Catalyst for Direct Aryl C-H Olefination

The efficient and selective palladium-catalyzed activation of C-H bonds is of great importance for the construction of diverse bioactive molecules. Despite significant progress, the inability to recycle palladium catalysts and the need for additives impedes the practical applications of these reactions. Ag₁ Pd₁ nanoparticles-reduced graphene oxide (Ag₁ Pd₁ -rGO) was used as highly efficient and recyclable catalyst for the chelation-assisted ortho C-H bond olefination of amides with acrylates in good yields with a broad substrate scope. The catalyst can be recovered and reused at least 5 times without losing activity. A synergistic effect between the Ag and Pd atoms on the catalytic activity was found, and a plausible mechanism for the AgPd-rGO catalyzed C-H olefination is proposed. These findings suggest that the search for such Pd-based bimetallic alloy nanoparticles is a new method towards the development of superior recyclable catalysts for direct aryl C-H functionalization under mild conditions.

Discovery of 2-(pyridin-2-yl)aniline as a directing group for the sp2 C–H bond amination mediated by cupric acetate

2-(Pyridin-2-yl) aniline was designed as a new, removable directing group in promoting C–H amination mediated by cupric acetate.

Computational study on NHC-catalyzed enantioselective and chemoselective fluorination of aliphatic aldehydes

A mechanistic study on NHC-catalyzed enantioselective and chemoselective fluorination of aliphatic aldehydes has been performed for the first time.

Copper(ii) catalyzed synthesis of novel helical luminescent benzo[4,5]imidazo[1,2-a][1,10]phenanthrolines via an intramolecular C–H amination reaction

Novel helical luminescent benzoimidazophenanthrolines were prepared using a Cu(ii) catalyzed C–H amination reaction.