Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Electrophilic aromatic substitution of a BN indole.

ABSTRACT: We report the first examples of a "BN-fused" indole, and we demonstrate that this new family of unnatural indole derivatives undergoes electrophilic aromatic substitution (EAS) reactions with the same regioselectivity as its organic analogue. Competition experiments reveal that N-t-Bu-BN-indole is more nucleophilic in EAS reactions than its carbonaceous counterpart. X-ray structural analysis between BN indole and classic indole highlights significant differences in bond distances, in particular for bonds associated with the boron atom.

SUBMITTER: Abbey ER

PROVIDER: S-EPMC2990470 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Electrophilic aromatic substitution of a BN indole.

Abbey Eric R ER Zakharov Lev N LN Liu Shih-Yuan SY

Journal of the American Chemical Society 20101102 46

We report the first examples of a "BN-fused" indole, and we demonstrate that this new family of unnatural indole derivatives undergoes electrophilic aromatic substitution (EAS) reactions with the same regioselectivity as its organic analogue. Competition experiments reveal that N-t-Bu-BN-indole is more nucleophilic in EAS reactions than its carbonaceous counterpart. X-ray structural analysis between BN indole and classic indole highlights significant differences in bond distances, in particular ...[more]

PMID: 21043508

Similar Datasets

Arenium ions are not obligatory intermediates in electrophilic aromatic substitution.

Project description:Our computational and experimental investigation of the reaction of anisole with Cl2 in nonpolar CCl4 solution challenges two fundamental tenets of the traditional SEAr (arenium ion) mechanism of aromatic electrophilic substitution. Instead of this direct substitution process, the alternative addition-elimination (AE) pathway is favored energetically. This AE mechanism rationalizes the preferred ortho and para substitution orientation of anisole easily. Moreover, neither the SEAr nor the AE mechanisms involve the formation of a ?-complex (Wheland-type) intermediate in the rate-controlling stage. Contrary to the conventional interpretations, the substitution (SEAr) mechanism proceeds concertedly via a single transition state. Experimental NMR investigations of the anisole chlorination reaction course at various temperatures reveal the formation of tetrachloro addition by-products and thus support the computed addition-elimination mechanism of anisole chlorination in nonpolar media. The important autocatalytic effect of the HCl reaction product was confirmed by spectroscopic (UV-visible) investigations and by HCl-augmented computational modeling.

| S-EPMC4104905 | biostudies-other

Precise through-space control of an abiotic electrophilic aromatic substitution reaction.

Project description:Nature has evolved selective enzymes for the efficient biosynthesis of complex products. This exceptional ability stems from adapted enzymatic pockets, which geometrically constrain reactants and stabilize specific reactive intermediates by placing electron-donating/accepting residues nearby. Here we perform an abiotic electrophilic aromatic substitution reaction, which is directed precisely through space. Ester arms-positioned above the planes of aromatic rings-enable it to distinguish between nearly identical, neighbouring reactive positions. Quantum mechanical calculations show that, in two competing reaction pathways, both [C-H···O]-hydrogen bonding and electrophile preorganization by coordination to a carbonyl group likely play a role in controlling the reaction. These through-space-directed mechanisms are inspired by dimethylallyl tryptophan synthases, which direct biological electrophilic aromatic substitutions by preorganizing dimethylallyl cations and by stabilizing reactive intermediates with [C-H···N]-hydrogen bonding. Our results demonstrate how the third dimension above and underneath aromatic rings can be exploited to precisely control electrophilic aromatic substitutions.

| S-EPMC5382318 | biostudies-literature

Fast and accurate prediction of the regioselectivity of electrophilic aromatic substitution reactions.

Project description:While computational prediction of chemical reactivity is possible it usually requires expert knowledge and there are relatively few computational tools that can be used by a bench chemist to help guide synthesis. The RegioSQM method for predicting the regioselectivity of electrophilic aromatic substitution reactions of heteroaromatic systems is presented in this paper. RegioSQM protonates all aromatic C-H carbon atoms and identifies those with the lowest free energies in chloroform using the PM3 semiempirical method as the most nucleophilic center. These positions are found to correlate qualitatively with the regiochemical outcome in a retrospective analysis of 96% of more than 525 literature examples of electrophilic aromatic halogenation reactions. The method is automated and requires only a SMILES string of the molecule of interest, which can easily be generated using chemical drawing programs such as ChemDraw. The computational cost is 1-10 minutes per molecule depending on size, using relatively modest computational resources and the method is freely available via a web server at ; http://www.regiosqm.org. RegioSQM should therefore be of practical use in the planning of organic synthesis.

| S-EPMC5869546 | biostudies-literature

A versatile route to edge-specific modifications to pristine graphene by electrophilic aromatic substitution.

Project description:Electrophilic aromatic substitution produces edge-specific modifications to CVD graphene and graphene nanoplatelets that are suitable for specific attachment of biomolecules.

| S-EPMC7266800 | biostudies-literature

Prediction of the Synthesis of Spiro Derivatives by Double Intramolecular Aromatic Electrophilic Substitution Using Reactivity Indices.

Project description:The synthesis of heterocyclic spirobifluorene (SBF) analogs generally requires long and complicated synthetic pathways. Despite this synthetic effort, such structural modification allows the (opto)electronic properties of this remarkable three-dimensional node to be tuned especially for molecular electronic applications. For this reason, the development of a simple, robust, and efficient synthetic methodology to introduce various heterocycles in place of classical phenyl rings in the spirofluorene motif is highly and timely desirable. In this context, we describe herein our efforts to develop a straightforward and efficient synthesis leading to replacement of 2 phenyl rings by various heterocycles in spiro compounds from 2,2'-dibromobenzophenone. As the same procedure to form fully heterocyclic compounds failed, an original theoretical approach based mainly on the uncommon Fukui dual function was developed in order to determine clearly the limitation of this strategy and provide an efficient predictive tool. Indeed, such calculation allows prediction of the thermodynamic and kinetic aspects of the synthesis of spiro derivatives using a double aromatic electrophilic substitution. If this procedure reproduces well our experimental results focused on (heterocyclic) SBF compounds, it can be certainly adapted and generalized to other intramolecular substitutions.

| S-EPMC6647987 | biostudies-literature

Cation-π binding ability of BN indole.

Project description:A BN indole-containing aromatic scaffold has been synthesized and the cation-π binding ability characterized by nuclear magnetic resonance (NMR) monitored titrations. The resulting chemical shifts were analyzed using a non-linear curve fitting procedure and the extracted association constants (Ka's) compared with the natural indole scaffold. Computations were also performed to support our findings. This work shows that incorporation of a B-N bond in place of a C-C bond in an aromatic system slightly lowers the cation-π binding ability of the arene's π-system with simple cations.

| S-EPMC7182272 | biostudies-literature

Desulfination by 2'-hydroxybiphenyl-2-sulfinate desulfinase proceeds via electrophilic aromatic substitution by the cysteine-27 proton.

Project description:Biodesulfurization is an attractive option for enzymatically removing sulfur from the recalcitrant thiophenic derivatives that comprise the majority of organosulfur compounds remaining in hydrotreated petroleum products. Desulfurization in the bacteria Rhodococcus erythropolis follows a four-step pathway culminating in C-S bond cleavage in the 2'-hydroxybiphenyl-2-sulfinate (HBPS) intermediate to yield 2-hydroxybiphenyl and bisulfite. The reaction, catalyzed by 2'-hydroxybiphenyl-2-sulfinate desulfinase (DszB), is the rate-limiting step and also the least understood, as experimental evidence points to a mechanism unlike that of other desulfinases. On the basis of structural and biochemical evidence, two possible mechanisms have been proposed: nucleophilic addition and electrophilic aromatic substitution. Density functional theory calculations showed that electrophilic substitution by a proton is the lower energy pathway and is consistent with previous kinetic and site-directed mutagenesis studies. C27 transfers its proton to HBPS, leading directly to the release of SO2 without the formation of a carbocation intermediate. The H60-S25 dyad stabilizes the transition state by withdrawing the developing negative charge on cysteine. Establishing the desulfination mechanism and specific role of active site residues, accomplished in this study, is essential to protein engineering efforts to increase DszB catalytic activity, which is currently too low for industrial-scale application.

| S-EPMC6100217 | biostudies-literature

Synthesis of Functional Fluorescent BODIPY-based Dyes through Electrophilic Aromatic Substitution: Straightforward Approach towards Customized Fluorescent Probes.

Project description:Fluorescent materials are widely used in biological and material applications as probes for imaging or sensing; however, their customization is usually complicated without the support of an organic chemistry laboratory. Here, we present a straightforward method for the customization of BODIPY cores, which are among the most commonly used fluorescent probes. The method is based on the formation of a new C-C bond through Friedel-Crafts electrophilic aromatic substitution carried out at room temperature. The method presented can be used to obtain completely customized fluorescent materials in one or two steps from commercially available compounds. Examples of the preparation of fluorescent materials for cell staining and functionalization of silica colloids are also presented.

| S-EPMC5062010 | biostudies-literature

Synthesis of pH indicators for Cerenkov imaging by electrophilic substitution of bromine by fluorine in an aromatic system.

Project description:Direct electrophilic fluorination using molecular fluorine gas is used in organic synthesis to create novel fluorine-containing compounds with potential beneficial activity that could not be obtained by nucleophilic substitution. In this paper, we report a novel electrophilic substitution of bromine by fluorine in an aromatic system. The mechanism of this type of fluorination was explored using the reaction between bromothymolsulfonphthalein (Bromothymol Blue) and dilute fluorine gas under acidic conditions. Substitution occurs in the bromine atoms located in the ortho-position relative to the hydroxyl group. A similar electrophilic fluorination of thymolsulfonphthalein (Thymol Blue) leads to a substitution of hydrogen atoms in the same position (ortho to hydroxyl). NMR spectroscopy was used to confirm the fluorination sites. NMR spectra of thymolsulfonphthalein and its derivatives under basic conditions can be explained by considering the absence of resonance between the two phenolic rings. Both dibromothymol blue and fluorobromothymol blue revealed intermolecular attenuate Cerenkov radiation selectively near their maximum absorbance in a pH dependent manner.

| S-EPMC5630228 | biostudies-literature

Boron in disguise: the parent "fused" BN indole.

Project description:"Fused" BN indoles are an emerging class of boron-containing indole mimics, featuring geometric structure and electophilic aromatic substitution reactivity similar to those of indoles but exhibiting distinct electronic structure, leading to unique optoelectronic properties. Herein we report the synthesis of the parent N-H BN indole and provide a head-to-head comparison of the structural features, pK(a) values, and optoelectronic properties of this hybrid organic/inorganic indole with the classic natural indole.

| S-EPMC3150194 | biostudies-other

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

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