Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Synthesis of pyridines from ketoximes and terminal alkynes via C-H bond functionalization.

ABSTRACT: An expedient one-pot rhodium catalyzed C-H bond functionalization/electrocyclization/dehydration procedure has been developed for the synthesis of highly substituted pyridine derivatives from terminal alkynes and ?,?-unsaturated ketoximes. The use of electron-deficient phosphite ligands is important to suppress dimerization of the terminal alkynes to enynes.

SUBMITTER: Martin RM

PROVIDER: S-EPMC3292635 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Synthesis of pyridines from ketoximes and terminal alkynes via C-H bond functionalization.

Martin Rhia M RM Bergman Robert G RG Ellman Jonathan A JA

The Journal of organic chemistry 20120214 5

An expedient one-pot rhodium catalyzed C-H bond functionalization/electrocyclization/dehydration procedure has been developed for the synthesis of highly substituted pyridine derivatives from terminal alkynes and α,β-unsaturated ketoximes. The use of electron-deficient phosphite ligands is important to suppress dimerization of the terminal alkynes to enynes. ...[more]

PMID: 22332639

Similar Datasets

Synthesis of dihydropyridines and pyridines from imines and alkynes via C-H activation.

Project description:A convenient one-pot C-H alkenylation/electrocyclization/aromatization sequence has been developed for the synthesis of highly substituted pyridine derivatives from alkynes and alpha,beta-unsaturated N-benzyl aldimines and ketimines that proceeds through dihydropyridine intermediates. A new class of ligands for C-H activation was developed, providing broader scope for the alkenylation step than could be achieved with previously reported ligands. Substantial information was obtained about the mechanism of the reaction. This included the isolation of a C-H activated complex and its structure determination by X-ray analysis; in addition, kinetic simulations using the Copasi software were employed to determine rate constants for this transformation, implicating facile C-H oxidative addition and slow reductive elimination steps.

| S-EPMC3057408 | biostudies-literature

Photochemical Organocatalytic Functionalization of Pyridines via Pyridinyl Radicals.

Project description:We report a photochemical method for the functionalization of pyridines with radicals derived from allylic C-H bonds. Overall, two substrates undergo C-H functionalization to form a new C(sp2)-C(sp3) bond. The chemistry harnesses the unique reactivity of pyridinyl radicals, generated upon single-electron reduction of pyridinium ions, which undergo effective coupling with allylic radicals. This novel mechanism enables distinct positional selectivity for pyridine functionalization that diverges from classical Minisci chemistry. Crucial was the identification of a dithiophosphoric acid that masters three catalytic tasks, sequentially acting as a Brønsted acid for pyridine protonation, a single electron transfer (SET) reductant for pyridinium ion reduction, and a hydrogen atom abstractor for the activation of allylic C(sp3)-H bonds. The resulting pyridinyl and allylic radicals then couple with high regioselectivity.

| S-EPMC9837848 | biostudies-literature

Synthesis of Stereodefined 1,1-Diborylalkenes via Copper-Catalyzed Diboration of Terminal Alkynes.

Project description:A copper-catalyzed method for the E-selective 1,1-diboration of terminal alkynes is described. The tandem process involves sequential dehydrogenative borylation of the alkyne substrate with HBdan (1,8-diaminonaphthalatoborane), followed by hydroboration with HBpin (pinacolborane). This method proceeds efficiently under mild conditions, furnishing 1,1-diborylalkenes with excellent stereoselectivity and broad functional group tolerance. Taking advantage of the different reactivities of the two boryl moieties, the products can then be employed in stepwise cross-couplings with aryl halides for the stereocontrolled construction of trisubstituted alkenes.

| S-EPMC7391966 | biostudies-literature

Access to pyrrolo-pyridines by gold-catalyzed hydroarylation of pyrroles tethered to terminal alkynes.

Project description:In a simple procedure, the intramolecular hydroarylation of N-propargyl-pyrrole-2-carboxamides was accomplished with the aid of gold(III) catalysis. The reaction led to differently substituted pyrrolo[2,3-c]pyridine and pyrrolo[3,2-c]pyridine derivatives arising either from direct cyclization or from a formal rearrangement of the carboxamide group. Terminal alkynes are essential to achieve bicyclic pyrrolo-fused pyridinones by a 6-exo-dig process, while the presence of a phenyl group at the C-C triple bond promotes the 7-endo-dig cyclization giving pyrrolo-azepines.

| S-EPMC3252845 | biostudies-literature

Asymmetric synthesis of ?-branched amines via Rh(III)-catalyzed C-H bond functionalization.

Project description:The first asymmetric intermolecular addition of non-acidic C-H bonds to imines is reported. The use of the activating N-perfluorobutanesulfinyl imine substituent is essential for achieving sufficient reactivity and provides outstanding diastereoselectivity (>98:2 dr). Straightforward removal of the sulfinyl group with HCl yields the highly enantiomerically enriched amine hydrochlorides.

| S-EPMC4105057 | biostudies-literature

Synthesis of multicyclic pyridine and quinoline derivatives via intramolecular C-H bond functionalization.

Project description:An efficient method is reported for the preparation of multicyclic pyridines and quinolines by a rhodium-catalyzed intramolecular C-H bond functionalization process. The method shows good scope for branched and unbranched alkyl substituents on the pyridine ring and at the R position of the tethered alkene group. Starting materials capable of undergoing olefin isomerization to provide terminal 1,1-disubstituted alkenes also proved to be effective substrates.

| S-EPMC2892546 | biostudies-literature

Efficient Pd-catalyzed coupling of tautomerizable heterocycles with terminal alkynes via C-OH bond activation using PyBrOP.

Project description:The direct alkynylation of tautomerizable heterocylcles is described via a two-step process involving in situ C-OH activation with bromotripyrrolidinophosphonium hexafluorophosphate (PyBrOP) followed by Sonogashira coupling with a wide range of alkyl or aryl terminal alkynes using a copper-free system employing PdCl(2)(CH(3)CN)(2) and 2-(dicyclohexylphosphino)biphenyl.

| S-EPMC2873160 | biostudies-literature

Synthesis of propargyl silanes from terminal alkynes <i>via</i> a migratory Sonogashira reaction.

Project description:Herein we report a mild synthesis of propargyl silanes from terminal alkynes. We exploit a bromonaphthyl-substituted silane as a silylmethyl electrophile surrogate, which participates in a Sonogashira reaction after an aryl-to-alkyl Pd-migration. Twenty-seven propargyl silanes were obtained in up to 88% yield. The obtained products were versatile building blocks that can be used in addition to electrophiles, triple bond hydrogenation or silyl group cleavage with acid or fluoride sources.

| S-EPMC10286695 | biostudies-literature

Synthesis of novel alkynyl imidazopyridinyl selenides: copper-catalyzed tandem selenation of selenium with 2-arylimidazo[1,2-<i>a</i>]pyridines and terminal alkynes.

Project description:Alkynyl selenides have attracted considerable research interest recently, owing to their applications in the biological and pharmaceutical fields. The Cu-catalyzed tandem reaction for the synthesis of novel alkynyl imidazopyridinyl selenides is presented. A one-pot synthesis route afforded alkynyl imidazopyridinyl selenides in moderate to good yields. This was achieved by a two-step reaction between terminal alkynes and diimidazopyridinyl diselenides, generated from imidazo[1,2-a]pyridines and Se powder, using 10 mol % of CuI and 1,10-phenanthroline as the catalytic system under aerobic conditions. The C(sp2)-Se and C(sp)-Se bond-formation reaction can be performed in one-pot by using inexpensive and easy to handle Se powder as the Se source. The reaction proceeded with terminal alkynes having various substitutions, such as aryl, vinyl, and alkyl groups. The obtained alkynyl imidazopyridinyl selenide was found to undergo nucleophilic substitution reaction on Se atom using organolithium reagents and 1,3-dipolar azide-alkyne cycloaddition based on the alkyne moiety.

| S-EPMC9344556 | biostudies-literature

Synthesis of Isomerically Pure (Z)-Alkenes from Terminal Alkynes and Terminal Alkenes: Silver-Catalyzed Hydroalkylation of Alkynes.

Project description:Alkenes are an important class of compounds common among biologically active molecules and often are used as intermediates in organic synthesis. Many alkenes exist in two stereoisomeric forms (E and Z), which have different structures and different properties. The selective formation of the two isomers is an important synthetic goal that has long inspired the development of new synthetic methods. However, the efficient synthesis of diastereopure, thermodynamically less stable, Z-alkenes is still challenging. Here, we demonstrate an efficient synthesis of diastereopure Z-alkenes (Z:E > 300:1) through a silver-catalyzed hydroalkylation of terminal alkynes, using alkylboranes as coupling partners. We also describe the exploration of the substrate scope, which reveals the broad functional group compatibility of the new method. Preliminary mechanistic studies suggest that a 1,2-metalate rearrangement of the silver borate intermediate is the key step responsible for the stereochemical outcome of the reaction.

| S-EPMC7304281 | 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