Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Reactions of (trialkylsilyl)vinylketenes with lithium ynolates: a new benzannulation strategy.

ABSTRACT: (Trialkylsilyl)vinylketenes react with lithium ynolates to produce highly substituted phenols in a new benzannulation strategy that proceeds via the 6pi electrocyclization of an intermediate 3-(oxido)dienylketene. [reaction: see text]

SUBMITTER: Austin WF

PROVIDER: S-EPMC2897055 | biostudies-literature | 2005 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Reactions of (trialkylsilyl)vinylketenes with lithium ynolates: a new benzannulation strategy.

Austin Wesley F WF Zhang Yongjun Y Danheiser Rick L RL

Organic letters 20050901 18

(Trialkylsilyl)vinylketenes react with lithium ynolates to produce highly substituted phenols in a new benzannulation strategy that proceeds via the 6pi electrocyclization of an intermediate 3-(oxido)dienylketene. [reaction: see text] ...[more]

PMID: 16119928

Similar Datasets

The use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines.

Project description:BackgroundChiral base desymmetrisation of dimethyl sulfoximines could provide a general route to chiral, enantioenriched dialkyl sulfoximines with potential for use in asymmetric catalysis.ResultsAsymmetric deprotonation of N-trialkylsilyl dimethyl sulfoximines with either enantiomer of lithium N,N-bis(1-phenylethyl)amide in the presence of lithium chloride affords enantioenriched sulfoximines on electrophilic trapping. Ketones, ketimines, trialkylsilyl chlorides and activated alkyl halides may be used as electrophiles in the reaction. Furthermore, a modified Horner-Emmons methodology was investigated.ConclusionSimple chiral lithium amides afford products with enantiomeric excesses of up to 70%, illustrating that chiral base desymmetrisation of dimethyl sulfoximines is possible.

| S-EPMC2100055 | biostudies-literature

Total Synthesis of Terpenoids Employing a "Benzannulation of Carvone" Strategy: Synthesis of (-)-Crotogoudin.

Project description:Carvone is a sustainable and readily available starting material for organic synthesis. Herein, we present the syntheses of various natural product scaffolds that rely on a novel benzannulation involving the ?-methyl group (C-10) of carvone to afford a versatile tetralin. The utility of our synthetic approach is highlighted by its application to a short synthesis of the ent-3,4-seco-atisane diterpenoid (-)-crotogoudin. The 13-step enantiospecific synthesis features a regioselective double oxidative dearomatization, a Diels-Alder cycloaddition with ethylene gas (to construct the bicyclo[2.2.2]octane framework), and a final acid-mediated lactonization. The versatility of this benzannulation strategy is demonstrated by its utility in the preparation of the carbon skeleton of ent-3,4-seco-abietane diterpenoids using an intramolecular oxidative dearomatization.

| S-EPMC6309435 | biostudies-literature

Rational design of spontaneous reactions for protecting porous lithium electrodes in lithium-sulfur batteries.

Project description:A rechargeable lithium anode requires a porous structure for a high capacity, and a stable electrode/electrolyte interface against dendrite formation and polysulfide crossover when used in a lithium-sulfur battery. Here, we design two simple steps of spontaneous reactions for protecting porous lithium electrodes. First, a reaction between molten lithium and sulfur-impregnated carbon nanofiber forms a fibrous network with a lithium shell and a carbon core. Second, we coat the surface of this porous lithium electrode with a composite of lithium bismuth alloys and lithium fluoride through another spontaneous reaction between lithium and bismuth trifluoride, solvated with phosphorous pentasulfide, which also polymerizes with lithium sulfide residual in the electrode to form a solid electrolyte layer. This protected porous lithium electrode enables stable operation of a lithium-sulfur battery with a sulfur loading of 10.2 mg cm-2 at 6.0 mA cm-2 for 200 cycles.

| S-EPMC6642196 | biostudies-literature

Tuning wettability of molten lithium via a chemical strategy for lithium metal anodes.

Project description:Metallic lithium affords the highest theoretical capacity and lowest electrochemical potential and is viewed as a leading contender as an anode for high-energy-density rechargeable batteries. However, the poor wettability of molten lithium does not allow it to spread across the surface of lithiophobic substrates, hindering the production and application of this anode. Here we report a general chemical strategy to overcome this dilemma by reacting molten lithium with functional organic coatings or elemental additives. The Gibbs formation energy and newly formed chemical bonds are found to be the governing factor for the wetting behavior. As a result of the improved wettability, a series of ultrathin lithium of 10-20 μm thick is obtained together with impressive electrochemical performance in lithium metal batteries. These findings provide an overall guide for tuning the wettability of molten lithium and offer an affordable strategy for the large-scale production of ultrathin lithium, and could be further extended to other alkali metals, such as sodium and potassium.

| S-EPMC6821877 | biostudies-other

A new design strategy for redox-active molecular assemblies with crystalline porous structures for lithium-ion batteries.

Project description:A new design strategy for high-performance organic cathode active materials for lithium-ion batteries is presented, which involves the assembly of redox-active organic molecules with a crystalline porous structure using mixed-stacked charge-transfer (CT) complexes. Hexahydroxytriphenylene was used as a donor molecule and 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-hexacarbonitrile as an acceptor molecule to give a new porous CT complex (PCT-1) with a pseudo-hexagonal mixed columnar structure. X-ray diffraction measurements and sorption experiments demonstrated that the intercolumnar spaces in PCT-1 can incorporate various molecules accompanied by lattice expansion. A lithium metal battery containing PCT-1 as a cathode active material exhibited a high capacity of 288 mA h g-1 at 500 mA g-1, and this performance was attributed to a combination of the redox-active units and the porous structure of PCT-1.

| S-EPMC7067258 | biostudies-literature

A practical guide for using lithium halocarbenoids in homologation reactions.

Project description:AbstractLithium halocarbenoids are versatile reagents for accomplishing homologation processes. The fast ?-elimination they suffer has been considered an important limitation for their extensive use. Herein, we present a series of practical considerations for an effective employment in the homologation of selected carbon electrophiles.Graphical abstract

| S-EPMC6006224 | biostudies-literature

A general method for Suzuki-Miyaura coupling reactions using lithium triisopropyl borates.

Project description:Conditions for the Suzuki-Miyaura coupling of lithium triisopropyl borates are reported, as well as a procedure for a one-pot lithiation, borylation, and subsequent Suzuki-Miyaura coupling of various heterocycles with aryl halides. These borate species are much more stable toward protodeboronation than the corresponding boronic acids and can conveniently be stored on benchtop at room temperature.

| S-EPMC3684691 | biostudies-literature

High-Entropy Catalysis Accelerating Stepwise Sulfur Redox Reactions for Lithium-Sulfur Batteries.

Project description:Catalysis is crucial to improve redox kinetics in lithium-sulfur (Li-S) batteries. However, conventional catalysts that consist of a single metal element are incapable of accelerating stepwise sulfur redox reactions which involve 16-electron transfer and multiple Li2Sn (n = 2-8) intermediate species. To enable fast kinetics of Li-S batteries, it is proposed to use high-entropy alloy (HEA) nanocatalysts, which are demonstrated effective to adsorb lithium polysulfides and accelerate their redox kinetics. The incorporation of multiple elements (Co, Ni, Fe, Pd, and V) within HEAs greatly enhances the catalytically active sites, which not only improves the rate capability, but also elevates the cycling stability of the assembled batteries. Consequently, HEA-catalyzed Li-S batteries achieve a high capacity up to 1364 mAh g-1 at 0.1 C and experience only a slight capacity fading rate of 0.054% per cycle over 1000 cycles at 2 C, while the assembled pouch cell achieves a high specific capacity of 1192 mAh g-1. The superior performance of Li-S batteries demonstrates the effectiveness of the HEA catalysts with maximized synergistic effect for accelerating S conversion reactions, which opens a way to catalytically improving stepwise electrochemical conversion reactions.

| S-EPMC11336958 | biostudies-literature

New Strategy To Access Enantioenriched Cyclohexadienones: Kinetic Resolution of <i>para</i>-Quinols by Organocatalytic Thiol-Michael Addition Reactions.

Project description:Existing stereoselective routes to 2,5-cyclohexadienones involve either desymmetrization of an achiral substrate or have attempted to perform an asymmetric dearomatization of a phenol. Herein, we report proof-of-principle experiments aimed at developing a kinetic resolution as an alternative method for accessing enantioenriched 2,5-cyclohexadienones. More specifically, chiral bifunctional thiourea catalysts were used to promote the addition of 2-thionapthalene into unsymmetric para-quinols. The selectivity of the kinetic resolution was found to be quite sensitive to substitution around the substrate.

| S-EPMC6643461 | biostudies-literature

Gold-catalyzed double migration-benzannulation cascade toward naphthalenes.

Project description:A novel gold(I)-catalyzed cycloisomerization of propargylic esters leading to unsymmetrically substituted naphthalenes has been developed. This cascade reaction involves an unprecedented tandem sequence of 1,3- and 1,2-migration of two different migrating groups. It is believed that this transformation likely proceeds via the formation of 1,3-diene intermediate or its precursor, which upon cyclization and aromatization steps transforms into the naphthalene core.

| S-EPMC3679922 | 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