C8–H bond activation vs. C2–H bond activation: from naphthyl amines to lactams

2016 ◽  
Vol 52 (90) ◽  
pp. 13307-13310 ◽  
Author(s):  
Renyi Shi ◽  
Lijun Lu ◽  
Hangyu Xie ◽  
Jingwen Yan ◽  
Ting Xu ◽  
...  
Keyword(s):  
Bond Activation ◽  
Amine Group ◽  
Easy Method ◽  
Bond Functionalization ◽  
Directing Group

Pd-catalyzed selective amine-oriented C8–H bond functionalization/N-dealkylative carbonylation of naphthyl amines has been achieved. The amine group from dealkylation is proposed to be the directing group for promoting this process. It represents a straightforward and easy method to access various biologically important benzo[cd]indol-2(1H)-one derivatives.

Remote meta C–H bond functionalization of 2-phenethylsulphonic acid and 3-phenylpropanoic acid derivatives

2016 ◽  
Vol 52 (96) ◽  
pp. 13916-13919 ◽  
Author(s):  
Atanu Modak ◽  
Anirban Mondal ◽  
Rahul Watile ◽  
Semanti Mukherjee ◽  
Debabrata Maiti
Keyword(s):  
Bond Activation ◽  
Acid Moiety ◽  
Bond Functionalization ◽  
Directing Group ◽  
Weakly Coordinating

This discovery illustrates selective meta C–H bond activation from multiple non-equivalent C–H bonds present in medicinally relevant arylethanesulfonic acid and the 2-arylpropanoic acid moiety using weakly coordinating nitrile as a directing group.

The Transient Directing Group Strategy: A New Trend in Transition-Metal-Catalyzed C–H Bond Functionalization

Synthesis ◽  
2017 ◽  
Vol 49 (21) ◽  
pp. 4808-4826 ◽  
Author(s):  
Tatiana Besset ◽  
Qun Zhao ◽  
Thomas Poisson ◽  
Xavier Pannecoucke
Keyword(s):  
Transition Metal ◽  
Bond Activation ◽  
Short Review ◽  
Point Of View ◽  
Bond Functionalization ◽  
Carbonyl Derivatives ◽  
Direct Functionalization ◽  
Directing Group ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

In recent years, the C–H bond activation field has known very fast expansion offering valuable synthetic tools. Consequently, the quest for new approaches to afford atom- and step-economical processes has driven the scientific community to imagine original strategies. In this context, the direct functionalization of substrates by a transition-metal-catalyzed C–H bond activation using a transient directing group has emerged as a promising approach. This short review focuses on the major progress made in this field to provide to the reader an overview of the recent advances.1 Introduction2 From a Historical Point of View3 Functionalization of Carbonyl Derivatives4 Functionalization of Amines Derivatives5 Summary and Outlook

Palladium-Catalyzed ortho-Monoacylation of Arenes with Aldehydes­ via 1,2,4-Benzotriazine-Directed C–H Bond Activation

Synthesis ◽  
2020 ◽  
Vol 52 (09) ◽  
pp. 1407-1416
Author(s):  
Bingcun Cui ◽  
Guosheng Huang ◽  
Jin Liu ◽  
Shaofen Jin ◽  
Yingxing Zhou ◽  
...  
Keyword(s):  
Functional Group ◽  
Bond Activation ◽  
Alternative Strategy ◽  
Bond Functionalization ◽  
Direct Modification ◽  
Palladium Catalyzed ◽  
Directing Group

An efficient palladium-catalyzed C–H bond functionalization/ortho-monoacylation reaction of 3-aryl-1,2,4-benzotriazines with (hetero)aryl or alkyl aldehydes has been developed, which offers a facile and alternative strategy for direct modification and further diversification of 3-aryl-1,2,4-benzotriazines. Bioactive 1,2,4-benzotriazine has been employed as a novel directing group for the palladium-catalyzed regioselective monoacylation of sp2 C–H bond protocol with broad substrate scope and good functional group tolerance.

Imine as a Linchpin Approach for Distal C(sp2)–H Functionalization

2020 ◽  
Author(s):  
Sukdev Bag ◽  
Sadhan Jana ◽  
Sukumar Pradhan ◽  
Suman Bhowmick ◽  
Nupur Goswami ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Activation ◽  
Bond Formation ◽  
Ancillary Ligand ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Directing Group ◽  
Covalently Linked ◽  
Complex Organic ◽  
Post Functionalization

<p>Despite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing group (DG) served as an ancillary ligand to ensure proximal <i>ortho</i>-, distal <i>meta</i>- and <i>para</i>-C-H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. We introduce here a transient directing group for distal C(<i>sp<sup>2</sup></i>)-H functionalization <i>via</i> reversible imine formation. By overruling facile proximal C-H bond activation by imine-<i>N</i> atom, a suitably designed pyrimidine-based transient directing group (TDG) successfully delivered selective distal C-C bond formation. Application of this transient directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the distal position has been explored.</p>

Theoretical and experimental studies of palladium-catalyzed site-selective C(sp3)−H bond functionalization enabled by transient ligands

2017 ◽  
Author(s):  
Haibo Ge ◽  
Lei Pan ◽  
Piaoping Tang ◽  
Ke Yang ◽  
Mian Wang ◽  
...  
Keyword(s):  
Bond Activation ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Bond Functionalization ◽  
Aliphatic Ketones ◽  
Site Selectivity ◽  
Mechanistic Investigation ◽  
Palladium Catalyzed ◽  
Metal Catalyzed ◽  
Site Selective

Transition metal-catalyzed selective C–H bond functionalization enabled by transient ligands has become an extremely attractive topic due to its economical and greener characteristics. However, catalytic pathways of this reaction process on unactivated sp<sup>3</sup> carbons of reactants have not been well studied yet. Herein, detailed mechanistic investigation on Pd-catalyzed C(sp<sup>3</sup>)–H bond activation with amino acids as transient ligands has been systematically conducted. The theoretical calculations showed that higher angle distortion of C(sp2)-H bond over C(sp3)-H bond and stronger nucleophilicity of benzylic anion over its aromatic counterpart, leading to higher reactivity of corresponding C(sp<sup>3</sup>)–H bonds; the angle strain of the directing rings of key intermediates determines the site-selectivity of aliphatic ketone substrates; replacement of glycine with β-alanine as the transient ligand can decrease the angle tension of the directing rings. Synthetic experiments have confirmed that β-alanine is indeed a more efficient transient ligand for arylation of β-secondary carbons of linear aliphatic ketones than its glycine counterpart.<br><br>

C-H bond functionalization using Pd and Au supported catalysts with mechanistic insights of the active species

Synthesis ◽  
2021 ◽  
Author(s):  
Tamao Ishida ◽  
Zhenzhong Zhang ◽  
Haruno Murayama ◽  
Eiji Yamamoto ◽  
Makoto Tokunaga
Keyword(s):  
Aromatic Compounds ◽  
Reaction Mechanisms ◽  
Bond Activation ◽  
Supported Catalysts ◽  
Metal Catalysts ◽  
Active Species ◽  
Supported Metal Catalysts ◽  
Bond Functionalization ◽  
Bond Forming ◽  
Supported Metal

The C–H functionalization has been extensively studied as a direct C–C bond forming reaction with high atomic efficiency. The efforts have also been made on the reaction using supported catalysts, which are superior in terms of catalyst separation from the reaction mixture and reusability. In this review, an overview of the C–H functionalization reactions, especially for Pd and Au supported catalysts will be described. In particular, we discuss reaction mechanisms, active species, leaching, reusability, etc. 1 Introduction 2 Types of supported metal catalysts and their active species 3 Modes of C–H bond activation 4 Oxidative C–H C–H coupling of aryl compounds 5 C–H C–H coupling where one side is aromatic 6 C–H acylation of aromatic compounds and related reactions 7 Conclusion

scholarly journals N-Benzo[c][1,2,5]thiazol-4-yl-3-trifluoromethylbenzamide

Molbank ◽  
10.3390/m1075 ◽  
2019 ◽  
Vol 2019 (3) ◽  
pp. M1075 ◽  
Author(s):  
Hamad H. Al Mamari ◽  
Nasser Al Awaimri ◽  
Yousuf Al Lawati
Keyword(s):  
1H Nmr ◽  
Elemental Analysis ◽  
13C Nmr ◽  
Title Compound ◽  
Structural Motif ◽  
Spectroscopic Methods ◽  
Bond Functionalization ◽  
Directing Group ◽  
Metal Catalyzed

The title compound, N-benzo[c][1,2,5]thiazol-4-yl-3-trifluoromethylbenzamide (1) was synthesized by reacting 3-trifluoromethylbenzoyl chloride (4) and 4-aminobenzo[c][1,2,5]thiadiazole (5). The compound was characterized by various spectroscopic methods (1H NMR, 13C NMR, IR, GC-MS) and its composition confirmed by elemental analysis. The importance of this compound lies in its possession of an N,N-bidentate directing group. Such a structural motif is potentially suitable for metal-catalyzed C-H bond functionalization reactions.

scholarly journals Palladium-Catalysed C–F Alumination of Fluorobenzenes: Mechanistic Diversity and Origin of Selectivity

2020 ◽  
Author(s):  
Feriel Rekhroukh ◽  
Wenyi Chen ◽  
Ryan Brown ◽  
Andrew J. P. White ◽  
Mark Crimmin
Keyword(s):  
Dft Calculations ◽  
Bond Activation ◽  
Oxidative Addition ◽  
Fluorine Content ◽  
Model Potential ◽  
Heterometallic Complex ◽  
Experimental Support ◽  
Highly Active ◽  
Reaction Proceeds ◽  
Directing Group

A palladium pre-catalyst, [Pd(PCy<sub>3</sub>)<sub>2</sub>] is reported for the efficient and selective C–F alumination of fluorobenzenes with the aluminium(I) reagent [{(ArNCMe)<sub>2</sub>CH}Al] (<b>1</b>, Ar = 2,6-di-iso-propylphenyl). The catalytic protocol results in the transformation of sp<sup>2</sup> C–F bonds to sp<sup>2</sup> C–Al bonds and provides a route into reactive organoaluminium complexes (<b>2a-h</b>) from fluorocarbons. The catalyst is highly active. Reactions proceed within 5 minutes at 25 ºC (and at appreciable rates at even –50 ºC) and the scope includes low-fluorine-content substrates such as fluorobenzene, difluorobenzenes and trifluorobenzenes. The reaction proceeds with complete chemoselectivity (C–F vs C–H) and high regioselectivities ( >90% for C–F bonds adjacent to the most acidic C–H sites). The heterometallic complex [Pd(PCy<sub>3</sub>)(<b>1</b>)<sub>2</sub>] was shown to be catalytically competent. Catalytic C–F alumination proceeds with a KIE of 1.1–1.3. DFT calculations have been used to model potential mechanisms for C–F bond activation. These calculations suggest that two competing mechanisms may be in operation. Pathway 1 involves a ligand-assisted oxidative addition to [Pd(<b>1</b>)<sub>2</sub>] and leads directly to the product. Pathway 2 involves a stepwise C–H to C–F functionalisation mechanism in which the C–H bond is broken and reformed along the reaction coordinate, allowing it to act as a directing group for the adjacent C–F site. This second mechanism explains the experimentally observed regioselectivity. Experimental support for this C–H activation playing a key role in C–F alumination was obtained by employing [{(MesNCMe)<sub>2</sub>CH}AlH<sub>2</sub>] (<b>3</b>, Mes = 2,4,6-trimethylphenyl) as a reagent in place of 1. In this instance, the kinetic C–H alumination intermediate could be isolated. Under catalytic conditions this intermediate converts to the thermodynamic C–F alumination product.

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