Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Seleniranium ion-triggered reactions: new aspects of Friedel-Crafts and N-detosylative cyclizations.

ABSTRACT: Seleniranium ions at low temperatures (-90 to -78 degrees C) will initiate effective Friedel-Crafts cyclization if a suitably placed arene is allowed to react even when the arene is unactivated. These intermediates generated from N-aryl-N-tosylamides undergo a novel, surprisingly efficient, detosylative cyclization to form 5- or 6-membered nitrogen heterocycles. A debenzylation route is preferred if both benzyl and tosyl groups are present in the substrate.

SUBMITTER: Lim HJ

PROVIDER: S-EPMC2742950 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Seleniranium ion-triggered reactions: new aspects of Friedel-Crafts and N-detosylative cyclizations.

Lim Hwan Jung HJ RajanBabu T V TV

Organic letters 20090701 13

Seleniranium ions at low temperatures (-90 to -78 degrees C) will initiate effective Friedel-Crafts cyclization if a suitably placed arene is allowed to react even when the arene is unactivated. These intermediates generated from N-aryl-N-tosylamides undergo a novel, surprisingly efficient, detosylative cyclization to form 5- or 6-membered nitrogen heterocycles. A debenzylation route is preferred if both benzyl and tosyl groups are present in the substrate. ...[more]

PMID: 19507847

Similar Datasets

Biocatalytic Friedel‐Crafts Reactions

Project description:Abstract Friedel‐Crafts alkylation and acylation reactions are important methodologies in synthetic and industrial chemistry for the construction of aryl‐alkyl and aryl‐acyl linkages that are ubiquitous in bioactive molecules. Nature also exploits these reactions in many biosynthetic processes. Much work has been done to expand the synthetic application of these enzymes to unnatural substrates through directed evolution. The promise of such biocatalysts is their potential to supersede inefficient and toxic chemical approaches to these reactions, with mild operating conditions ‐ the hallmark of enzymes. Complementary work has created many bio‐hybrid Friedel‐Crafts catalysts consisting of chemical catalysts anchored into biomolecular scaffolds, which display many of the same desirable characteristics. In this Review, we summarise these efforts, focussing on both mechanistic aspects and synthetic considerations, concluding with an overview of the frontiers of this field and routes towards more efficient and benign Friedel‐Crafts reactions for the future of humankind. Artificial enzymes: Friedel‐Crafts reactions are a mainstay methodology for organic chemists to construct aryl‐alkyl and aryl‐acyl linkages. Nature uses biocatalysts for performing such reactions to construct an array of bio‐active compounds. In this Review we discuss several examples of such enzymes, as well Friedel‐Crafts artificial enzymes and DNA catalysts, from the useful products they produce, to their mechanism and approaches for engineering.

| S-EPMC9804301 | biostudies-literature

Lewis acid-promoted Friedel-Crafts alkylation reactions with alpha-ketophosphate electrophiles.

Project description:The BF(3).OEt(2)-promoted nucleophilic substitution of alpha-aryl-alpha-ketophosphates to afford alpha,alpha-diaryl ketone products is described. Electron-rich alpha-ketophosphates perform best, with electron-neutral and electron-poor substrates also tolerated. The reaction is tolerant of a range of aromatic, heteroaromatic, and nonaromatic nucleophiles, with yields ranging from 44% to 84%. Enantioenriched starting material yields racemic product, suggesting an S(N)1 pathway via an acylcarbenium ion.

| S-EPMC2852482 | biostudies-literature

Mechanochemical Friedel-Crafts acylations.

Project description:Friedel-Crafts (FC) acylation reactions were exploited in the preparation of ketone-functionalized aromatics. Environmentally more friendly, solvent-free mechanochemical reaction conditions of this industrially important reaction were developed. Reaction parameters such as FC catalyst, time, ratio of reagents and milling support were studied to establish the optimal reaction conditions. The scope of the reaction was explored by employment of different aromatic hydrocarbons in conjunction with anhydrides and acylation reagents. It was shown that certain FC-reactive aromatics could be effectively functionalized by FC acylations carried out under ball-milling conditions without the presence of a solvent. The reaction mechanism was studied by in situ Raman and ex situ IR spectroscopy.

| S-EPMC6604704 | biostudies-literature

Friedel-Crafts acylation with amides.

Project description:Friedel-Crafts acylation has been known since the 1870s, and it is an important organic synthetic reaction leading to aromatic ketone products. Friedel-Crafts acylation is usually performed with carboxylic acid chlorides or anhydrides, while amides are generally not useful substrates in these reactions. Despite being the least reactive carboxylic acid derivative, we have found a series of amides capable of providing aromatic ketones in good yields (55-96%, 17 examples). We propose a mechanism involving diminished C-N resonance through superelectrophilic activation and subsequent cleavage to acyl cations.

| S-EPMC3402163 | biostudies-literature

Hafnium-Doped Mesoporous Silica as Efficient Lewis Acidic Catalyst for Friedel-Crafts Alkylation Reactions.

Project description:The development of an efficient solid catalyst for Friedel-Crafts (FC) reactions is of great importance to organic synthetic chemistry. Herein, we reported the hafnium-doped mesoporous silica catalyst Hf/SBA-15 and its first use for Friedel-Crafts alkylation reactions. Catalysts with different Si/Hf ratios were prepared and characterized, among which Hf/SBA-15(20) (Si/Hf = 20:1) was the most active catalyst, offering up to 99.1% benzylated product under mild reaction conditions. The influences of reaction conditions on the product were systematically investigated and compared. Pyridine-IR characterization of the catalyst showed that Lewis acid formed the primary active sites for the Friedel-Crafts alkylation reaction. X-ray photoelectron spectroscopy (XPS) characterization revealed that the electron shift from the Hf center to the silica framework resulted in a more active Lewis metal center for FC reactions. Moreover, the catalyst was successfully applied to the alkylation reaction with different alcohols and aromatic compounds. Finally, the Hf/SBA-15(20) catalyst also showed good recyclability in the recycling runs, demonstrating its high potential of being used for large scale FC reactions in the industry.

| S-EPMC6723505 | biostudies-literature

9-Membered carbocycle formation: development of distinct Friedel-Crafts cyclizations and application to a scalable total synthesis of (±)-caraphenol A.

Project description:Explorations into a series of different approaches for 9-membered carbocycle formation have afforded the first reported example of a 9-exo-dig ring closure via a Au(III)-promoted reaction between an alkyne and an aryl ring as well as several additional, unique Friedel-Crafts-type cyclizations. Analyses of the factors leading to the success of these transformations are provided, with the application of one of the developed 9-membered ring closures affording an efficient and scalable synthesis of the bioactive resveratrol trimer caraphenol A. That synthesis proceeded with an average yield of 89% per step (7.8% overall yield) and has provided access to more than 600 mg of the target molecule.

| S-EPMC4106019 | biostudies-literature

Artificial Metalloenzymes based on TetR Proteins and Cu(II) for Enantioselective Friedel-Crafts Alkylation Reactions.

Project description:The supramolecular approach is among the most convenient methodologies for creating artificial metalloenzymes (ArMs). Usually this approach involves the binding of a transition metal ion complex to a biomolecular scaffold via its ligand, which also modulates the catalytic properties of the metal ion. Herein, we report ArMs based on the proteins CgmR, RamR and QacR from the TetR family of multidrug resistance regulators (MDRs) and Cu2+ ions, assembled without the need of a ligand. These ArMs catalyze the enantioselective vinylogous Friedel-Crafts alkylation reaction with up to 75 % ee. Competition experiments with ethidium and rhodamine 6G confirm that the reactions occur in the chiral environment of the hydrophobic pocket. It is proposed that the Cu2+-substrate complex is bound via a combination of electrostatic and π-stacking interactions provided by the second coordination sphere. This approach constitutes a fast and straightforward way to assemble metalloenzymes and may facilitate future optimization of the protein scaffolds via mutagenesis or directed evolution approaches.

| S-EPMC7319431 | biostudies-literature

Three-component synthesis of new unsymmetrical oxindoles via Friedel-Crafts type reaction.

Project description:The synthesis of 2-(3-(4-(dimethylamino)phenyl)-2-oxoindolin-3-yl)-1H-indene-1,3(2H)-diones as new unsymmetrical oxindoles via a Friedel-Crafts type three-component reaction of 1,3-indandion, N,N-dimethylaniline and isatins in ethanol in the presence of LiClO4 is reported.

| S-EPMC7126103 | biostudies-literature

The enantioselective construction of tetracyclic diterpene skeletons with Friedel-Crafts alkylation and palladium-catalyzed cycloalkenylation reactions.

Project description:Due to the profound extent to which natural products inspire medicinal chemists in drug discovery, there is demand for innovative syntheses of these often complex materials. This article describes the synthesis of tricarbocyclic natural product architectures through an extension of the enantioselective Birch-Cope sequence with intramolecular Friedel-Crafts alkylation reactions. Additionally, palladium-catalyzed enol silane cycloalkenylation of the tricarbocyclic structures afforded the challenging bicyclo[3.2.1]octane C/D ring system found in the gibberellins and the ent-kauranes, two natural products with diverse medicinal value. In the case of the ent-kaurane derivative, an unprecedented alkene rearrangement converted four alkene isomers to one final product.

| S-EPMC4334740 | biostudies-literature

Friedel-Crafts Alkylation of Indoles with Trichloroacetimidates.

Project description:Substituted indole scaffolds are often utilized in medicinal chemistry as they regularly possess significant pharmacological activity. Therefore the development of simple, inexpensive and efficient methods for alkylating the indole heterocycle continues to be an active research area. Reported are reactions of trichloroacetimidate electrophiles and indoles to address the challenges of accessing alkyl decorated indole structures. These alkylations perform best when either the indole or the imidate is functionalized with electron withdrawing groups to avoid polyalkylation.

| S-EPMC6720118 | 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