Browse
Submit Data
Databases
API
Help

Dataset Information

28 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Ligand-Enabled Meta-C-H Alkylation and Arylation Using a Modified Norbornene.

ABSTRACT: 2-Carbomethoxynorbornene is identified as a more effective transient mediator to promote a Pd(II)-catalyzed meta-C(sp(2))-H alkylation of amides with various alkyl iodides as well as arylation with previously incompatible aryl iodides. The use of a tailor-made quinoline ligand is also crucial for this reaction to proceed.

SUBMITTER: Shen PX

PROVIDER: S-EPMC4573956 | biostudies-other | 2015 Sep

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Publications

Ligand-Enabled Meta-C-H Alkylation and Arylation Using a Modified Norbornene.

Shen Peng-Xiang PX Wang Xiao-Chen XC Wang Peng P Zhu Ru-Yi RY Yu Jin-Quan JQ

Journal of the American Chemical Society 20150903 36

2-Carbomethoxynorbornene is identified as a more effective transient mediator to promote a Pd(II)-catalyzed meta-C(sp(2))-H alkylation of amides with various alkyl iodides as well as arylation with previously incompatible aryl iodides. The use of a tailor-made quinoline ligand is also crucial for this reaction to proceed. ...[more]

PMID: 26313012

Similar Datasets

Ligand-Enabled Auxiliary-Free meta-C-H Arylation of Phenylacetic Acids.

Project description:The meta-C-H arylation of free phenylacetic acid was realized using 2-carbomethoxynorbornene (NBE-CO2 Me) as a transient mediator. Both the modified norbornene and the mono-protected 3-amino-2-hydroxypyridine type ligand are crucial for this auxiliary-free meta-C-H arylation reaction. A series of phenylacetic acids, including mandelic acid and phenylglycine, react smoothly with various aryl iodides to provide the meta-arylated products in high yields.

| S-EPMC5535739 | biostudies-literature

meta-C-H Arylation and Alkylation of Benzylsulfonamide Enabled by a Palladium(II)/Isoquinoline Catalyst.

Project description:Palladium(II)-catalyzed meta-C-H arylation and alkylation of benzylsulfonamide using 2-carbomethoxynorbornene (NBE-CO2 Me) as a transient mediator are realized by using a newly developed electron-deficient directing group and isoquinoline as a ligand. This protocol features broad substrate scope and excellent functional-group tolerance. The meta-substituted benyzlsulfonamides can be readily transformed into sodium sulfonates, sulfonate esters, and sulfonamides, as well as styrenes by Julia-type olefination. The unique impact of the isoquinoline ligand underscores the importance of subtle matching between ligands and the directing groups.

| S-EPMC5553125 | biostudies-literature

Ligand-Enabled Arylation of ?-C-H Bonds.

Project description:Pd(II) -catalyzed arylation of ?-C(sp(3) )-H bonds of aliphatic acid-derived amides was developed by using quinoline-based ligands. Various ?-aryl-?-amino acids were prepared from natural amino acids using this method. The influence of ligand structure on reactivity was also systematically investigated.

| S-EPMC4821162 | biostudies-literature

Ligand-Enabled meta-Selective C-H Arylation of Nosyl-Protected Phenethylamines, Benzylamines, and 2-Aryl Anilines.

Project description:A Pd-catalyzed, meta-selective C-H arylation of nosyl-protected phenethylamines and benzylamines is disclosed using a combination of norbornene and pyridine-based ligands. Subjecting nosyl protected 2-aryl anilines to this protocol led to meta-C-H arylation at the remote aryl ring. A diverse range of aryl iodides are tolerated in this reaction, along with select heteroaryl iodides. Select aryl bromides bearing ortho-coordinating groups can also be utilized as effective coupling partners in this reaction. The use of pyridine ligands has allowed the palladium loading to be reduced to 2.5 mol %. Furthermore, a catalytic amount of 2-norbornene (20 mol %) to mediate this meta-C-H activation process is demonstrated for the first time. Utilization of a common protecting group as the directing group for meta-C-H activation of amines is an important feature of this reaction in terms of practical applications.

| S-EPMC5497681 | biostudies-other

Ligand-enabled ?-C-H arylation of ?-amino acids using a simple and practical auxiliary.

Project description:Pd-catalyzed ?-C-H functionalizations of carboxylic acid derivatives using an auxiliary as a directing group have been extensively explored in the past decade. In comparison to the most widely used auxiliaries in asymmetric synthesis, the simplicity and practicality of the auxiliaries developed for C-H activation remains to be improved. We previously developed a simple N-methoxyamide auxiliary to direct ?-C-H activation, albeit this system was not compatible with carboxylic acids containing ?-hydrogen atoms. Herein we report the development of a pyridine-type ligand that overcomes this limitation of the N-methoxyamide auxiliary, leading to a significant improvement of ?-arylation of carboxylic acid derivatives, especially ?-amino acids. The arylation using this practical auxiliary is applied to the gram-scale syntheses of unnatural amino acids, bioactive molecules, and chiral bis(oxazoline) ligands.

| S-EPMC4432912 | biostudies-literature

Modular Entry to Functionalized Tetrahydrobenzo[<i>b</i>]azepines via the Palladium/Norbornene Cooperative Catalysis Enabled by a C7-Modified Norbornene.

Project description:Tetrahydrobenzo[b]azepines (THBAs) are commonly found in many bioactive compounds; however, the modular preparation of functionalized THBAs remains challenging to date. Here, we report a straightforward method to synthesize THBAs directly from simple aryl iodides via palladium/norbornene (Pd/NBE) cooperative catalysis. Capitalizing on an olefin-tethered electrophilic amine reagent, an ortho amination followed by 7-exo-trig Heck cyclization furnishes the seven-membered heterocycle. To overcome the difficulty with ortho-unsubstituted aryl iodide substrates, we discovered a unique C7-bromo-substituted NBE (N1) to offer the desired reactivity and selectivity. In addition to THBAs, synthesis of other benzo-seven-membered ring compounds can also be promoted by N1. Combined experimental and computational studies show that the C7-bromo group in N1 plays an important and versatile role in this catalysis, including promoting β-carbon elimination, suppressing benzocyclobutene formation, and stabilizing reaction intermediates. The mechanistic insights gained could guide future catalyst design. The synthetic utility has been demonstrated in a streamlined synthesis of tolvaptan and forming diverse pharmaceutically relevant THBA derivatives. Finally, a complementary and general catalytic condition to access C6-substituted THBAs from ortho-substituted aryl iodides has also been developed.

| S-EPMC9142336 | biostudies-literature

Ligand-Enabled, Palladium-Catalyzed ?-C(sp3)-H Arylation of Weinreb Amides.

Project description:We report the development of Pd(II)-catalyzed C(sp3)-H arylation of Weinreb amides. This work demonstrates the first example of using Weinreb amide as a directing group for transition metal-catalyzed C(sp3)-H activation. Both the inductive effect and the potential bidentate coordination mode of the Weinreb amides pose a unique challenge for this reaction development. A pyridinesulfonic acid ligand is designed to accommodate the weak, neutral coordinating property of Weinreb amides via preserving the cationic character of Pd center through zwitterionic assembly of Pd/ligand complexes. DFT studies of the C-H cleavage step indicate that the superior reactivity of 3-pyridinesulfonic acid ligand compared to pyridine, Ac-Gly-OH, and ligandless conditions originates from the stabilization of overall substrate-bound Pd species.

| S-EPMC6586421 | biostudies-literature

Ligand-enabled meta-C-H activation using a transient mediator.

Project description:Achieving site selectivity in C-H functionalization reactions is a significant challenge, especially when the target C-H bond is distant from existing functional groups. Coordination of a functional group to a metal is often a key driving force and control element in many important reactions including asymmetric hydrogenation, epoxidation and lithiation. Exploitation of this effect has led to the development of a broad range of directed C-H activation reactions. However, these C-H activation methods are limited to proximal C-H bonds, which are spatially and geometrically accessible from the directing functional group. The development of meta-selective C-H functionalizations remains a significant challenge. We recently developed a U-shaped template that can be used to overcome this constraint and have shown that it can be used to selectively activate remote meta-C-H bonds. Although this approach has proved to be applicable to various substrates and catalytic transformations, the need for a covalently attached, complex template is a substantial drawback for synthetic applications. Here we report an alternative approach employing norbornene as a transient mediator to achieve meta-selective C-H activation with a simple and common ortho-directing group. The use of a newly developed pyridine-based ligand is crucial for relaying the palladium catalyst to the meta position by norbornene after initial ortho-C-H activation. This catalytic reaction demonstrates the feasibility of switching ortho-selectivity to meta-selectivity in C-H activation of the same substrate by catalyst control.

| S-EPMC4368492 | biostudies-literature

Pd-catalysed ligand-enabled carboxylate-directed highly regioselective arylation of aliphatic acids.

Project description:?-amino acids bearing aromatic side chains are important synthetic units in the synthesis of peptides and natural products. Although various ?-C-H arylation methodologies for amino acid derivatives involving the assistance of directing groups have been extensively developed, syntheses that directly employ N-protected amino acids as starting materials remain rare. Herein, we report an N-acetylglycine-enabled Pd-catalysed carboxylate-directed ?-C(sp3)-H arylation of aliphatic acids. In this way, various non-natural amino acids can be directly prepared from phthaloylalanine in one step in good to excellent yields. Furthermore, a series of aliphatic acids have been shown to be amenable to this transformation, affording ?-arylated propionic acid derivatives in moderate to good yields. More importantly, this ligand-enabled direct ?-C(sp3)-H arylation could be easily scaled-up to 10?g under reflux conditions, highlighting the potential utility of this synthetic method.

| S-EPMC5384235 | biostudies-literature

Ligand-Enabled ?-C-H Arylation of ?-Amino Acids Without Installing Exogenous Directing Groups.

Project description:Herein we report acid-directed ?-C(sp3 )-H arylation of ?-amino acids enabled by pyridine-type ligands. This reaction does not require the installation of an exogenous directing group, is scalable, and enables the preparation of Fmoc-protected unnatural amino acids in three steps. The pyridine-type ligands are crucial for the development of this new C(sp3 )-H arylation.

| S-EPMC5302090 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data