Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Radical Hydrodehalogenation of Aryl Bromides and Chlorides with Sodium Hydride and 1,4-Dioxane.

ABSTRACT: A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4-dioxane as reagents and 1,10-phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism.

SUBMITTER: Hokamp T

PROVIDER: S-EPMC5698765 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Radical Hydrodehalogenation of Aryl Bromides and Chlorides with Sodium Hydride and 1,4-Dioxane.

Hokamp Tobias T Dewanji Abhishek A Lübbesmeyer Maximilian M Mück-Lichtenfeld Christian C Würthwein Ernst-Ulrich EU Studer Armido A

Angewandte Chemie (International ed. in English) 20170919 43

A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4-dioxane as reagents and 1,10-phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism. ...[more]

PMID: 28841248

Similar Datasets

Negishi coupling of secondary alkylzinc halides with aryl bromides and chlorides.

Project description:An efficient palladium-catalyzed process has been developed for Negishi coupling of secondary alkylzinc halides with a wide range of aryl bromides and activated aryl chlorides. A palladium catalyst composed of a new biaryldialkylphosphine ligand, CPhos, effectively promotes the rate of the reductive elimination step relative to the rate of the undesired beta-hydride elimination. The broad substrate scope and excellent ratio of the desired secondary to the undesired primary coupling product make this method a powerful and reliable tool for C(sp(3))-C(sp(2)) bond formation.

| S-EPMC2746668 | biostudies-literature

Palladium-catalyzed amination of aryl chlorides and bromides with ammonium salts.

Project description:We report the palladium-catalyzed coupling of aryl halides with ammonia and gaseous amines as their ammonium salts. The coupling of aryl chlorides and ortho-substituted aryl bromides with ammonium sulfate forms anilines with higher selectivity for the primary arylamine over the diarylamine than couplings with ammonia in dioxane. The resting state for the reactions of aryl chlorides is different from the resting state for the reactions of aryl bromides, and this change in resting states is proposed to account for a difference in selectivities for reactions of the two haloarenes.

| S-EPMC4260968 | biostudies-literature

A general, practical palladium-catalyzed cyanation of (hetero)aryl chlorides and bromides.

Project description:Playing it safe: The nontoxic cyanide source K4 [Fe(CN)6]·3H2O can be used for the cyanation of (hetero)aryl halides. The application of palladacycle catalysts prevents poisoning during catalyst formation, thereby allowing for low catalyst loadings, fast reaction times, and wide heterocyclic substrate scope.

| S-EPMC3845028 | biostudies-literature

Palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides.

Project description:The palladium-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) has been developed using dialkylbiaryl phosphine ligands. A variety of aryl, heteroaryl, and vinyl halides can be prepared via this method in good to excellent yields.

| S-EPMC2975586 | biostudies-literature

Aryl Bromides and Aryl Chlorides for the Direct Arylation of Benzylic Amines Mediated by Ruthenium(II).

Project description:The ruthenium(II)-catalyzed sp3 C-H bond arylation of benzylic amines with aryl halides is reported. In the present method, aryl iodides and, more importantly, also the cheaper aryl bromides and aryl chlorides can be applied as aryl sources. Additionally, the method does not require elaborate manipulations in a glove box and can be carried out in simple screw cap vials. Potassium pivalate proved to be beneficial for the transformation with aryl bromides or iodides as aryl source, but was not required for aryl chlorides. In the latter case, the addition of PPh3 led to high conversion. 3-Methyl and 3-phenyl pyridine were established as directing groups, and the substituent in the 3-position represents a key structural feature for high conversion. The directing group can be cleaved after the transformation, which allows access to diarylmethylamines. Mechanistic studies were carried out and critically compared to mechanistic reports of related transformations.

| S-EPMC3698694 | biostudies-literature

Palladium-catalyzed α-arylation of aryl acetic acid derivatives via dienolate intermediates with aryl chlorides and bromides.

Project description:To date, examples of α-arylation of carboxylic acids remain scarce. Using a deprotonative cross-coupling process (DCCP), a method for palladium-catalyzed γ-arylation of aryl acetic acids with aryl halides has been developed. This protocol is applicable to a wide range of aryl bromides and chlorides. A procedure for the palladium-catalyzed α-arylation of styryl acetic acids is also described.

| S-EPMC4610326 | biostudies-literature

An improved palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides.

Project description:A facile Pd-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) is described. This method allows convenient access to a variety of aryl, heteroaryl, and vinyl halides in good to excellent yields and with greatly simplified conditions relative to our previous report.

| S-EPMC3170430 | biostudies-literature

Photo-Induced, Phenylhydrazine-Promoted Transition-Metal-Free Dehalogenation of Aryl Fluorides, Chlorides, Bromides, and Iodides.

Project description:In this study, we present a straightforward and highly effective photo-triggered hydrogenation method for aryl halides, devoid of transition-metal catalysts. Through the synergistic utilization of light, PhNHNH2, and a base, we have successfully initiated the desired radical-mediated hydrogenation process. Remarkably, utilizing mild reaction conditions, a wide range of aryl halides, including fluorides, chlorides, bromides, and iodides, can be selectively transformed into their corresponding (hetero)arene counterparts, with exceptional yields. Additionally, this approach demonstrates a remarkable compatibility with diverse functional groups and heterocyclic compounds, highlighting its versatility and potential for use in various chemical transformations.

| S-EPMC10574415 | biostudies-literature

Replacing conventional carbon nucleophiles with electrophiles: nickel-catalyzed reductive alkylation of aryl bromides and chlorides.

Project description:A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons. Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields. Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes. The protocols are highly functional-group tolerant (-OH, -NHTs, -OAc, -OTs, -OTf, -COMe, -NHBoc, -NHCbz, -CN, -SO(2)Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture. The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki-Miyaura, Stille, and Hiyama-Denmark reactions. Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R-X) and no reaction at the nucleophilic carbon (R-[M]) for organoboron (-Bpin), organotin (-SnMe(3)), and organosilicon (-SiMe(2)OH) containing organic halides (X-R-[M]). A Hammett study showed a linear correlation of σ and σ(-) parameters with the relative rate of reaction of substituted aryl bromides with bromoalkanes. The small ρ values for these correlations (1.2-1.7) indicate that oxidative addition of the bromoarene is not the turnover-frequency determining step. The rate of reaction has a positive dependence on the concentration of alkyl bromide and catalyst, no dependence upon the amount of zinc (reducing agent), and an inverse dependence upon aryl halide concentration. These results and studies with an organic reductant (TDAE) argue against the intermediacy of organozinc reagents.

| S-EPMC3324882 | biostudies-literature

C-N Coupling of DNA-Conjugated (Hetero)aryl Bromides and Chlorides for DNA-Encoded Chemical Library Synthesis.

Project description:DNA-encoded chemical library (DECL) screens are a rapid and economical tool to identify chemical starting points for drug discovery. As a robust transformation for drug discovery, palladium-catalyzed C-N coupling is a valuable synthetic method for the construction of DECL chemical matter; however, currently disclosed methods have only been demonstrated on DNA-attached (hetero)aromatic iodide and bromide electrophiles. We developed conditions utilizing an N-heterocyclic carbene-palladium catalyst that extends this reaction to the coupling of DNA-conjugated (hetero)aromatic chlorides with (hetero)aromatic and select aliphatic amine nucleophiles. In addition, we evaluated steric and electronic effects within this catalyst series, carried out a large substrate scope study on two representative (hetero)aryl bromides, and applied this newly developed method within the construction of a 63 million-membered DECL.

| S-EPMC7086399 | 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