Browse
Submit Data
Databases
API
Help

Dataset Information

18 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Lewis base directed cycloaddition reactions of 2-pyrones and alkynylaluminum reagents.

ABSTRACT: In situ generated alkynylaluminum reagents have been utilized in a [4 + 2] cycloaddition with 2-pyrones bearing a Lewis basic donor. The reactions proceed at or below room temperature and with complete regiocontrol. This one-pot method affords diversely substituted aromatic compounds under very mild conditions.

SUBMITTER: Crepin DF

PROVIDER: S-EPMC3766945 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Design and reactions of a carbon Lewis base/boron Lewis acid frustrated Lewis pair.

Project description:The conjugated dienamine 4 selectively adds Piers' borane [HB(C6F5)2] to give the enamine/borane system 5, which features a boratirane structure by internal enamine carbon Lewis base to boron Lewis acid interaction. Compound 5 behaves as a C/B frustrated Lewis pair and undergoes typical addition reactions to benzaldehyde, several nitriles and to sulfur dioxide.This article is part of the themed issue 'Frustrated Lewis pair chemistry'.

| S-EPMC5540844 | biostudies-literature

Stereoselective Lewis base catalyzed formal 1,3-dipolar cycloaddition of azomethine imines with mixed anhydrides.

Project description:Stereoselective synthesis of pyrazolidinones via dipolar cycloaddition of azomethine imines with active esters under Lewis base catalysis is presented. The active esters are readily generated in situ from the corresponding acids. Products, which are obtained with excellent diastereocontrol and high enantioselectivity, contain along with the pyrazolidinone core also the tetrahydroisoquinoline structural motif. Theoretical studies give insight into the mechanism of the formal cycloaddition reaction.

| S-EPMC5811128 | biostudies-other

Regioselective Annulation of 6-Carboxy-Substituted Pyrones as a Two-Carbon Unit in Formal [4 + 2] Cycloaddition Reactions.

Project description:Heterocycles serve as a critical motif in chemistry, but despite being present in more than 85% of pharmaceuticals, there are limited methods for their construction. Here, we describe the incorporation of intact pyrone (2H-pyran-2-one) into larger ring systems via annulation. In a formal [4 + 2] cycloaddition, the pyrone regioselectively accepts a benzylic anion as a nucleophile in a conjugate addition fashion, with the subsequent pyrone-derived enolate attaching to a pendant ester on the initial nucleophile. Subsequent base-driven enolate formation and elimination establish aromaticity of the newly formed ring. After optimization of this process using an NMR-based assessment to overcome solubility and separation challenges, the reaction was successfully applied to a library of 6-ester and -amide-substituted pyrones and using a phenyl ester and other substituted sulfoxides. This technology enables the incorporation of intact pyrone rings into more complex systems, such as for the total synthesis of the natural product thermorubin.

| S-EPMC11232011 | biostudies-literature

SET processes in Lewis acid-base reactions: the tritylation of N-heterocyclic carbenes.

Project description:Reactions between N-heterocyclic carbenes (NHCs) and the trityl cation, [Ph3C]+, give covalent adducts of type [NHC-CPh3]+ and/or [NHC-C6H5-CPh2]+. EPR spectroscopy, UV-Vis analyses, and trapping experiments imply that adduct formation involves carbene radical cations and the trityl radical. The results demonstrate that single electron transfer (SET) processes should be considered for reaction of NHCs with oxidizing Lewis acids.

| S-EPMC8159480 | biostudies-literature

How the Lewis Base F<sup>-</sup> Catalyzes the 1,3-Dipolar Cycloaddition between Carbon Dioxide and Nitrilimines.

Project description:The mechanism of the Lewis base F- catalyzed 1,3-dipolar cycloaddition between CO2 and nitrilimines is interrogated using DFT calculations. F- activates the nitrilimine, not CO2 as proposed in the literature, and imparts a significant rate enhancement for the cycloaddition. The origin of this catalysis is in the strength of the primary orbital interactions between the reactants. The Lewis base activated nitrilimine-F- has high-lying filled FMOs. The smaller FMO-LUMO gap promotes a rapid nucleophilic attack and overall cycloaddition with CO2.

| S-EPMC8023701 | biostudies-literature

Environmentally Benign Lewis Acid Promoted [2+3]-Dipolar Cycloaddition Reactions of Nitrile Imines with Alkenes in Water.

Project description:Mild and environmentally benign Lewis acid promoted 1,3-dipolar cycloaddition reactions of α-hydrazonyl chlorides with alkenes in water are reported. These α-hydrazonyl chlorides, in the presence of Lewis acids, generate nitrile imines in situ which react with dipolarophiles to furnish the corresponding cycloaddition products. In many cases, the required times for the completion of the Lewis acid promoted 1,3-dipolar cycloaddition reactions in water were comparable to the equivalent reactions performed in an organic solvent. Analogous tetrahexylammonium chloride promoted 1,3-dipolar cycloaddition reactions were also performed. The comparison of reaction times and cycloadduct yields for the aforementioned 1,3-dipolar reactions in aqueous and organic media as well as the proposed role of the Lewis acid in the 1,3-dipolar cycloaddition reaction are described.

| S-EPMC3957226 | biostudies-literature

Syntheses of ?-pyrones using gold-catalyzed coupling reactions.

Project description:Sequential alkyne activation of terminal alkynes and propiolic acids by gold(I) catalysts yields compounds having ?-pyrone skeletons. Novel cascade reactions involving propiolic acids are reported that give rise to ?-pyrones with different substitution patterns.

| S-EPMC3103191 | biostudies-literature

Formal [3+2] Cycloaddition Reactions of Electron-Rich Aryl Epoxides with Alkenes under Lewis Acid Catalysis Affording Tetrasubstituted Tetrahydrofurans.

Project description:We report on the regio- and stereoselective synthesis of tetrahydrofurans by reaction between epoxides and alkenes in the presence of a Lewis acid. This is an unprecedented formal [3+2] cycloaddition reaction between an epoxide and an alkene. The chemical reaction represents a very concise synthesis of tetrahydrofurans from accessible starting compounds.

| S-EPMC7036929 | biostudies-literature

Cycloaddition reactions for antiviral compounds

Project description:Prominent in the current stage of drug development, antiviral compounds can be efficiently prepared through cycloaddition reactions. The chapter reports the use of classical Diels–Alder and their hetero version for the design and synthesis of compounds that were tested for their antiviral activities against a variety of viruses. Furthermore, 1,3-dipolar cycloaddition reactions of selected 1,3-dipoles, such as azides, nitrones, and nitrile oxides, are reviewed in the light of their application in the preparation of key intermediates for antiviral synthesis. A few examples of [2+2] cycloaddition reactions are also presented. The products obtained from these pericyclic reaction approaches were all tested for their activities in terms of blocking the virus replication, and the relevant biological data are highlighted.

| S-EPMC7149647 | biostudies-literature

Lewis Base Activation of Lewis Acid: A Detailed Bond Analysis.

Project description:The effect of a Lewis base (LB) on the nucleophilic attack on chalcogeniranium (chalcogen = sulfur and selenium) cations, the so-called LB activation of a Lewis acid, has been studied coupling natural orbital for chemical valence decomposition of the orbital interaction energy with charge displacement analysis. This methodology provides a detailed and accurate description of all the interactions (LB···chalcogen, chalcogen···olefin and olefin···ammonia) present in the system and leads to a deeper understanding of how they influence each other at all stages of the reaction: reactant complex, transition state, and product complex. In particular, the bond between the chalcogen and the olefin has been decomposed in terms of σ donation/π back-donation and the bond components quantified. This allowed determination of a linear relationship between the activation barrier of the nucleophilic attack and the net amount of charge donated by the olefin to the chalcogen.

| S-EPMC6643480 | 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