Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Palladium-catalyzed ortho-halogenations of acetanilides with N-halosuccinimides via direct sp2 C-H bond activation in ball mills.

ABSTRACT: A solvent-free palladium-catalyzed ortho-iodination of acetanilides using N-iodosuccinimide as the iodine source has been developed under ball-milling conditions. This present method avoids the use of hazardous organic solvents, high reaction temperature, and long reaction time and provides a highly efficient methodology to realize the regioselective functionalization of acetanilides in yields up to 94% in a ball mill. Furthermore, the current methodology can be extended to the synthesis of ortho-brominated and ortho-chlorinated products in good yields by using the corresponding N-halosuccinimides.

SUBMITTER: Liu Z

PROVIDER: S-EPMC5827707 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Palladium-catalyzed ortho-halogenations of acetanilides with N-halosuccinimides via direct sp2 C-H bond activation in ball mills.

Liu Zi Z Xu Hui H Wang Guan-Wu GW

Beilstein journal of organic chemistry 20180216

A solvent-free palladium-catalyzed ortho-iodination of acetanilides using N-iodosuccinimide as the iodine source has been developed under ball-milling conditions. This present method avoids the use of hazardous organic solvents, high reaction temperature, and long reaction time and provides a highly efficient methodology to realize the regioselective functionalization of acetanilides in yields up to 94% in a ball mill. Furthermore, the current methodology can be extended to the syn ...[more]

PMID: 29520307

Similar Datasets

Modular synthesis of dihydro-isoquinolines: palladium-catalyzed sequential C(sp2)-H and C(sp3)-H bond activation.

Project description:An efficient synthesis of dihydro-isoquinolines via a Pd-catalyzed double C-H bond [a C(sp2)-H and a C(sp3)-H bond] activation/annulation (CHAA) reaction is presented. This methodology features a short reaction time, high atom economy (loss of H2O only) and the formation of a sterically less favoured tertiary C-N bond. This fast (30 min) and environmentally benign radical C-H activation approach has demonstrated the potential direction for the future design/development of fast and efficient C-H direct functionalization processes.

| S-EPMC5950195 | biostudies-other

Palladium(II)-Catalyzed Tandem Oxidative Acetoxylation/ortho C-H Activation/Carbocyclization of Arylallenes.

Project description:Herein we report an example of tandem oxidative acetoxylation/carbocyclization of arylallenes 1 using Pd(OAc)2. The catalytic protocol is highly selective and provides access to new C-C and C-O bonds leading to a carbocyclization. The reaction proceeds via C-H activation by Pd. Mechanistic investigations show that the C-H activation is not the rate-limiting step and indicate that the reaction proceeds via acetoxylation of the allene.

| S-EPMC4557776 | biostudies-literature

Palladium-Catalyzed Chemoselective Activation of sp3 vs sp2 C-H Bonds: Oxidative Coupling To Form Quaternary Centers.

Project description:The oxidative activation of alkyl C-H bonds vs arene C-H bonds with Pd(OAc)2 has been found to be generalizable to a number of nucleophilic substrates allowing the formation of a range of hindered quaternary centers. The substrates share a common mechanistic path wherein Pd(II) initiates an oxidative dimerization. The resultant dimer modifies the palladium catalyst to favor activation of alkyl C-H bonds in contrast to the trends typically observed via a concerted metalation deprotonation mechanism. Notably, insertion occurs at the terminus of the alkyl arene for hindered substrates. Two different oxidant systems were discovered that turn over the process. Parameters have been identified that predict, which substrates are productive in this reaction.

| S-EPMC6880961 | biostudies-literature

Twofold C-H functionalization: palladium-catalyzed ortho arylation of anilides.

Project description:The ortho arylation of anilides to form biphenyls via a twofold C-H functionalization/C-C bond-forming process is described. The oxidative coupling takes place in the presence of 5-10 mol % of Pd(OAc)2, 10-20 mol % of DMSO, and 4-11 equiv of the aryl substrate in TFA under an oxygen atmosphere. No metal-containing cocatalyst is required.

| S-EPMC2489205 | biostudies-literature

Mechanistic Model for Enantioselective Intramolecular Alkene Cyanoamidation via Palladium-Catalyzed C-CN Bond Activation.

Project description:We studied key aspects of the mechanism of Pd-catalyzed C-CN bond activation and intramolecular enantioselective alkene cyanoamidation. An Abboud-Abraham-Kamlet-Taft (AAKT) linear solvation energy relationship (LSER) model for enantioselectivity was established. We investigated the impact of Lewis acid (BPh3), Lewis base (DMPU), and no additives. BPh3 additive led to diminished enantioselectivity and differing results in 13CN crossover experiments, initial rate kinetics, and natural abundance 12C/13C kinetic isotope effect measurements. We propose two catalytic mechanisms to account for our experimental results. We propose that the DMPU/nonadditive pathway passes through a ?2-phosphoramidite-stabilized Pd+ intermediate, resulting in high enantioselectivity. BPh3 prevents the dissociation of CN-, leading to a less rigid ?2-phosphoramidite-neutral Pd intermediate.

| S-EPMC5535300 | biostudies-literature

Palladium-catalyzed decarbonylative Suzuki-Miyaura cross-coupling of amides by carbon-nitrogen bond activation.

Project description:Palladium-catalyzed Suzuki-Miyaura cross-coupling or aryl halides is widely employed in the synthesis of many important molecules in synthetic chemistry, including pharmaceuticals, polymers and functional materials. Herein, we disclose the first palladium-catalyzed decarbonylative Suzuki-Miyaura cross-coupling of amides for the synthesis of biaryls through the selective activation of the N-C(O) bond of amides. This new method relies on the precise sequence engineering of the catalytic cycle, wherein decarbonylation occurs prior to the transmetallation step. The reaction is compatible with a wide range of boronic acids and amides, providing valuable biaryls in high yields (>60 examples). DFT studies support a mechanism involving oxidative addition, decarbonylation and transmetallation and provide insight into high N-C(O) bond activation selectivity. Most crucially, the reaction establishes the use of palladium catalysis in the biaryl Suzuki-Miyaura cross-coupling of the amide bond and should enable the design of a wide variety of cross-coupling methods in which palladium rivals the traditional biaryl synthesis from aryl halides and pseudohalides.

| S-EPMC6977462 | biostudies-literature

Is silver a mere terminal oxidant in palladium catalyzed C-H bond activation reactions?

Project description:In the contemporary practice of palladium catalysis, a molecular understanding of the role of vital additives used in such reactions continues to remain rather vague. Herein, we disclose an intriguing and a potentially general role for one of the most commonly used silver salt additives, discovered through rigorous computational investigations on four diverse Pd-catalyzed C-H bond activation reactions involving sp2 aryl C-H bonds. The catalytic pathways of different reactions such as phosphorylation, arylation, alkynylation, and oxidative cycloaddition are analyzed, with and without the explicit inclusion of the silver additive in the respective transition states and intermediates. Our results indicate that the pivotal role of silver salts is likely to manifest in the form of a Pd-Ag heterobimetallic species that facilitates intermetallic electronic communication. The Pd-Ag interaction is found to provide a consistently lower energetic span as compared to an analogous pathway devoid of such interaction. Identification of a lower energy pathway as well as enhanced catalytic efficiency due to Pd-Ag interaction could have broad practical implications in the mechanism of transition metal catalysis and the current perceptions on the same.

| S-EPMC7012060 | biostudies-literature

Palladium-Catalyzed Decarboxylative Ortho-Acylation of Tertiary Benzamides with Arylglyoxylic Acids.

Project description:A palladium-catalyzed ortho-acylation of tertiary benzamides using arylglyoxylic acids has been described. Unlike the palladium insertion reported to occur in the distorted N-C(O) amide bond of tertiary benzamides, the current study unveils ortho C-H palladation in acylic or cyclic N,N-dialkylbenzamides affording ortho-acylated tertiary benzamides in good to excellent yields. Our experimental study on the mechanism provides information on the tendency of the amide nitrogen toward weak coordination with palladium as opposed to oxygen. However, density functional theory calculations suggest coordination of amide oxygen to palladium, which makes the mechanism especially interesting. A Pd(II)/Pd(III) catalytic cycle and nucleophilic attack by the acyl radical rather than arylglyoxylate anion are supported by mechanistic studies.

| S-EPMC6641690 | biostudies-literature

Auxiliary-assisted palladium-catalyzed arylation and alkylation of sp2 and sp3 carbon-hydrogen bonds.

Project description:We have developed a method for auxiliary-directed, palladium-catalyzed beta-arylation and alkylation of sp(3) and sp(2) C-H bonds in carboxylic acid derivatives. The method employs a carboxylic acid 2-methylthioaniline- or 8-aminoquinoline amide substrate, aryl or alkyl iodide coupling partner, palladium acetate catalyst, and an inorganic base. By employing 2-methylthioaniline auxiliary, selective monoarylation of primary sp(3) C-H bonds can be achieved. If arylation of secondary sp(3) C-H bonds is desired, 8-aminoquinoline auxiliary may be used. For alkylation of sp(3) and sp(2) C-H bonds, 8-aminoquinoline auxiliary affords the best results. Some functional group tolerance is observed and amino- and hydroxy-acid derivatives can be functionalized. Preliminary mechanistic studies have been performed. A palladacycle intermediate has been isolated, characterized by X-ray crystallography, and its reactions have been studied.

| S-EPMC2841226 | biostudies-literature

Palladium-Catalyzed C-H Bond Acetoxylation via Electrochemical Oxidation.

Project description:Here we describe the development of a method for the Pd-catalyzed electrochemical acetoxylation of C-H bonds. The oxidation step of the catalytic cycle is probed through cyclic voltammetry and bulk electrolysis studies of a preformed palladacycle of 8-methylquinoline. A catalytic system for C-H acetoxylation is then developed and optimized with respect to the cell configuration, rate of oxidation, and chemistry at the counter electrode. This transformation is then applied to substrates containing various directing groups and to the acetoxylation of both C(sp2)-H and C(sp3)-H bonds.

| S-EPMC5772685 | biostudies-literature