Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Direct transition-metal-free intramolecular arylation of phenols.

ABSTRACT: Direct transition-metal-free, base-mediated intramolecular arylation of phenols with aryl halides has been developed. In the presence of 2.5 equiv of t-BuOK in dioxane at 140 degrees C, the intramolecular cyclization of 3-(2-halobenzyloxy)phenols affords 6H-benzo[c]chromenes in high yields. This reaction proceeds by an initial formation of a benzyne intermediate followed by an aromatic sp(2) C-H functionalization (a formal C-H activation) to form the carbon-carbon bond.

SUBMITTER: Bajracharya GB

PROVIDER: S-EPMC2627406 | biostudies-literature | 2008 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Direct transition-metal-free intramolecular arylation of phenols.

Bajracharya Gan B GB Daugulis Olafs O

Organic letters 20080918 20

Direct transition-metal-free, base-mediated intramolecular arylation of phenols with aryl halides has been developed. In the presence of 2.5 equiv of t-BuOK in dioxane at 140 degrees C, the intramolecular cyclization of 3-(2-halobenzyloxy)phenols affords 6H-benzo[c]chromenes in high yields. This reaction proceeds by an initial formation of a benzyne intermediate followed by an aromatic sp(2) C-H functionalization (a formal C-H activation) to form the carbon-carbon bond. ...[more]

PMID: 18798647

Similar Datasets

Transition-Metal Catalyst Free Oxidative Radical Arylation of N-Methylpyrrole.

Project description:This study represents an expansion of the application of catalysis in air through conventional coupling and free radical processes. A reactive free aryl radical intermediate was generated via the oxidation of an activated Ar-NH-NH2 bond by air as a simple and readily available oxidant. For this purpose, the usability of phenylhydrazine and phenylhydrazine hydrochloride salt reagents for the direct arylation of pyrrole with aryl radicals was investigated. The facile coupling of N-methylpyrrole with aryl radicals was easily applied for the convenient direct synthesis of C-2 arylated pyrroles without a transition-metal catalyst.

| S-EPMC6641933 | biostudies-literature

Transition Metal-Free N-Arylation of Amino Acid Esters with Diaryliodonium Salts.

Project description:A transition metal-free approach for the N-arylation of amino acid derivatives has been developed. Key to this method is the use of unsymmetric diaryliodonium salts with anisyl ligands, which proved important to obtain high chemoselectivity and yields. The scope includes the transfer of both electron deficient, electron rich and sterically hindered aryl groups with a variety of different functional groups. Furthermore, a cyclic diaryliodonium salt was successfully employed in the arylation. The N-arylated products were obtained with retained enantiomeric excess.

| S-EPMC8048889 | biostudies-literature

Transition metal-free direct dehydrogenative arylation of activated C(sp3)-H bonds: synthetic ambit and DFT reactivity predictions.

Project description:A transition metal-free dehydrogenative method for the direct mono-arylation of a wide range of activated C(sp3)-H bonds has been developed. This operationally simple and environmentally friendly aerobic arylation uses tert-BuOK as the base and nitroarenes as electrophiles to prepare up to gram quantities of structurally diverse sets (>60 examples) of ?-arylated esters, amides, nitriles, sulfones and triaryl methanes. DFT calculations provided a predictive model, which states that substrates containing a C(sp3)-H bond with a sufficiently low pK a value should readily undergo arylation. The DFT prediction was confirmed through experimental testing of nearly a dozen substrates containing activated C(sp3)-H bonds. This arylation method was also used in a one-pot protocol to synthesize over twenty compounds containing all-carbon quaternary centers.

| S-EPMC6202766 | biostudies-literature

Transition metal-free intramolecular regioselective couplings of aliphatic and aromatic C-H bonds.

Project description:Cross-dehydrogenative couplings of two different C-H bonds have emerged as an attractive goal in organic synthesis. However, achieving regioselective C-H activation is a great challenge because C-H bonds are ubiquitous in organic compounds. Actually, the regioselective couplings promoted by enzymes are a common occurrence in nature. Herein, we have developed simple, efficient and general transition metal-free intramolecular couplings of alphatic and aromatic C-H bonds. The protocol uses readily available aryl triazene as the radical initiator, cheap K2S2O8 as the oxidant, and the couplings were performed well with excellent tolerance of functional groups. Interestingly, ?-carbon configuration of some amino acid residues in the substrates was kept after the reactions, and the couplings for substrates with substituted phenylalanine residues exhibited complete ?-carbon diastereoselectivity for induction of the chiral ?-carbon. Therefore, the present study should provide a novel strategy for regioselective cross-dehydrogenative couplings of two different C-H bonds.

| S-EPMC4731807 | biostudies-other

Transition-metal-free α-arylation of oxindoles via visible-light-promoted electron transfer.

Project description:An operationally simple photochemical strategy for the direct arylation of oxindoles with (hetero)aryl halides in the absence of both transition metals and photoredox catalysts has been developed. The reaction provides an efficient way to construct various 3-aryloxindole building blocks of pharmaceutical interest at ambient temperature by using household compact fluorescent light (CFL) bulbs as the light source. Preliminarily, mechanistic studies revealed that the intermolecular electron transfer relied on the formation of photon-absorbing electron-donor-acceptor (EDA) complexes between electron-rich oxindole enolates and electron-deficient (hetero)aryl halides, and a radical chain mechanism was operative.

| S-EPMC6427940 | biostudies-literature

Room temperature, metal-free arylation of aliphatic alcohols.

Project description:Diaryliodonium salts are demonstrated as efficient arylating agents of aliphatic alcohols under metal-free conditions. The reaction proceeds at room temperature within 90 min to give alkyl aryl ethers in good to excellent yields. Aryl groups with electron-withdrawing substituents are transferred most efficiently, and unsymmetric iodonium salts give chemoselective arylations. The methodology has been applied to the formal synthesis of butoxycaine.

| S-EPMC4000167 | biostudies-literature

Palladium-catalyzed direct ?-arylation of ketones with diaryliodonium salts: a stoichiometric heavy metal-free and user-friendly approach.

Project description:We herein report a new protocol for the Pd-catalyzed ?-arylation of ketones without stoichiometric heavy metals. Widely accessible diaryliodonium salts are used as both the oxidant and aryl source. This tandem redox catalysis merges ketone dehydrogenation and conjugate addition without an additional oxidant or reductant. This transformation features the use of a unique bis-N-tosylsulfilimine ligand and the combination of potassium trifluoroacetate/trifluoroacetic acid to maintain an appropriate acidity of the reaction medium. The reaction tolerates both air and moisture, and shows a broad substrate scope. Kinetics studies, along with filtration and poisoning tests, support the involvement of palladium nanoparticles in the catalysis.

| S-EPMC5949602 | biostudies-literature

Intramolecular hydride transfer onto arynes: redox-neutral and transition metal-free C(sp3)-H functionalization of amines.

Project description:Transition metal-free intramolecular hydride transfer onto arynes is reported for the first time. This unique transformation is utilized in redox-neutral intermolecular ?-functionalization reactions of different tertiary amines, generating C(sp3)-C(sp3/sp2/sp) bonds in a single synthetic operation. Deuterium labeling studies support initial cleavage of the ?-C-H bond via intramolecular 1,5-hydride transfer onto the aryne, which leads to activation of a range of integrated pronucleophiles and ultimately affords a new approach to cross-dehydrogenative coupling reactions which utilize aryne intermediates.

| S-EPMC5914459 | biostudies-literature

Metal-free defluorinative arylation of trifluoromethyl alkenes via photoredox catalysis.

Project description:Literature methods to access gem-difluoroalkenes are largely limited to harsh, organometallic-based methods, and known photoredox-mediated processes are not amenable to aryl radical addition to trifluoromethyl alkenes. A metal-free, functional group-tolerant method for the preparation of benzylic gem-difluoroalkenes is described. Halogen atom abstraction from (hetero)aryl halides generates aryl radicals that undergo a defluorinative arylation of ?-trifluoromethyl alkenes, tolerating electronically disparate aryl radicals and ?-trifluoromethyl alkenes.

| S-EPMC7210470 | biostudies-literature

Metal-free C-H arylation of imidazoheterocycles with aryl hydrazines.

Project description:A simple and efficient metal-free arylation of imidazo[1,2-a]pyridines at the C-3 position with arylhydrazine has been achieved at room temperature under ambient air conditions. Various 2,3-disubstituted imidazopyridines and imidazothiazoles were synthesized with high yields. The present methodology demonstrates the usefulness of commercially available aryl hydrazine as an arylating agent.

| S-EPMC9079221 | 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