Browse
Submit Data
Databases
API
Help

Dataset Information

20 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Metal-Free Hydrosilylation of Ketenes with Silicon Electrophiles: Access to Fully Substituted Aldehyde-Derived Silyl Enol Ethers.

ABSTRACT: Little-explored hydrosilylation of ketenes promoted by main-group catalysts is reported. The boron Lewis acid tris(pentafluorophenyl)borane accelerates the slow uncatalyzed reaction of ketenes and hydrosilanes, thereby providing a convenient access to the new class of β,β-di- and β-monoaryl-substituted aldehyde-derived silyl enol ethers. Yields are moderate to high, and Z configuration is preferred. The corresponding silyl bis-enol ethers are also available when using dihydrosilanes. The related trityl-cation-initiated hydrosilylation involving self-regeneration of silylium ions is far less effective.

SUBMITTER: Roy A

PROVIDER: S-EPMC8251732 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Photoredox-catalyzed silyldifluoromethylation of silyl enol ethers.

Project description:A method for the light-mediated fluoroalkylation of silyl enol ethers with (bromodifluoromethyl)trimethylsilane followed by a reduction of the primary products with sodium borohydride is described. An 18 W, 375 nm LED was used as the light source. The reaction is performed in the presence of a gold photocatalyst, which effects the generation of a (trimethylsilyl)difluoromethyl radical via cleavage of the carbon-bromine bond.

| S-EPMC7356207 | biostudies-literature

Catalytic asymmetric defluorinative allylation of silyl enol ethers.

Project description:The stereocontrolled installation of alkyl fragments at the alpha position of ketones is a fundamental yet unresolved transformation in organic chemistry. Herein we report a new catalytic methodology able to construct α-allyl ketones via defluorinative allylation of silyl enol ethers in a regio-, diastereo- and enantioselective manner. The protocol leverages the unique features of the fluorine atom to simultaneously act as a leaving group and to activate the fluorophilic nucleophile via a Si-F interaction. A series of spectroscopic, electroanalytic and kinetic experiments demonstrate the crucial interplay of the Si-F interaction for successful reactivity and selectivity. The generality of the transformation is demonstrated by synthesising a wide set of structurally diverse α-allylated ketones bearing two contiguous stereocenters. Remarkably, the catalytic protocol is amenable for the allylation of biologically significant natural products.

| S-EPMC10321495 | biostudies-literature

FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers.

Project description:Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6-tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ-terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).

| S-EPMC6207922 | biostudies-literature

Synthesis of 2-substituted 7-hydroxybenzofuran-4-carboxylates via addition of silyl enol ethers to o-benzoquinone esters.

Project description:Mukaiyama Michael addition of silyl enol ethers 13 to the 1,2-quinone-4-carboxylate 6 (formed in situ by oxidation of the catechol ester 8) afforded the 2-subsituted 7-hydroxybenzofuran-4-carboxylates 14 in fair to good yields. Alkyl and aryl systems work well, but highly electron-rich silyl enol ethers could not be used because of competing oxidation.

| S-EPMC2784895 | biostudies-literature

Enantioselective α-functionalizations of ketones via allylic substitution of silyl enol ethers.

Project description:The enantioselective construction of carbon-heteroatom and carbon-carbon bonds that are alpha to ketones leads to the formation of substructures that are ubiquitous in natural products, pharmaceuticals and agrochemicals. Traditional methods to form such bonds have relied on combining ketone enolates with electrophiles. Reactions with heteroatom-based electrophiles require special reagents in which the heteroatom, which is typically nucleophilic, has been rendered electrophilic by changes to the oxidation state. The resulting products usually require post-synthetic transformations to unveil the functional group in the final desired products. Moreover, different catalytic systems are typically required for the reaction of different electrophiles. Here, we report a strategy for the formal enantioselective α-functionalization of ketones to form products containing a diverse array of substituents at the alpha position with a single catalyst. This strategy involves an unusual reversal of the role of the nucleophile and electrophile to form C-N, C-O, C-S and C-C bonds from a series of masked ketone electrophiles and a wide range of conventional heteroatom and carbon nucleophiles catalysed by a metallacyclic iridium catalyst.

| S-EPMC6347495 | biostudies-literature

Photoinduced Formation of Hybrid Aryl Pd-Radical Species Capable of 1,5-HAT: Selective Catalytic Oxidation of Silyl Ethers into Silyl Enol Ethers.

Project description:A direct visible light-induced generation of a hybrid aryl Pd-radical species from aryl iodide and Pd(0) is reported to enable an unprecedented (for hybrid Pd-radical species) hydrogen atom-transfer event. This approach allowed for efficient desaturation of readily available silyl ethers into synthetically valuable silyl enols. Moreover, this oxidation reaction proceeds at room temperature without the aid of exogenous photosensitizers or oxidants.

| S-EPMC7577783 | biostudies-literature

Silyl enol ether Prins cyclization: diastereoselective formation of substituted tetrahydropyran-4-ones.

Project description:A diastereoselective synthesis of cis-2,6-disubstituted tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydroxy silyl enol ether allowed for the formation of more than 30 new tetrahydropyran-4-ones with up to 97% yield and >95:5 dr. The cyclization step forms new carbon-carbon and carbon-oxygen bonds, as well as a quaternary center with good diastereoselectivity. The method provides a versatile route for the synthesis of substituted tetrahydropyrans.

| S-EPMC4168786 | biostudies-literature

N-triflylthiophosphoramide catalyzed enantioselective Mukaiyama aldol reaction of aldehydes with silyl enol ethers of ketones.

Project description:The first Brønsted acid catalyzed asymmetric Mukaiyama aldol reaction of aldehydes using silyl enol ethers of ketones as nucleophiles has been reported. A variety of aldehydes and silyl enol ethers of ketones afforded the aldol products in excellent yields and good to excellent enantioselectivities. Mechanistic studies revealed that the actual catalyst may be changed from the silylated Brønsted acid to the Brønsted acid itself depending on the reaction temperature.

| S-EPMC2887700 | biostudies-literature

Direct allylic C-H alkylation of enol silyl ethers enabled by photoredox-Bronsted base hybrid catalysis.

Project description:Strategies for altering the reaction pathway of reactive intermediates are of significant importance in diversifying organic synthesis. Enol silyl ethers, versatile enolate equivalents, are known to undergo one-electron oxidation to generate the radical cations that spontaneously form electrophilic α-carbonyl radicals via elimination of the silyl groups. Here, we demonstrate that close scrutiny of the property of the radical cations as strong C-H acids enables the identification of a catalyst system consisting of an iridium-based photosensitizer and 2,4,6-collidine for the generation of nucleophilic allylic radicals from enol silyl ethers through one-electron oxidation-deprotonation sequence under light irradiation without the desilylation of the radical cation intermediates. The resultant allylic radicals engage in the addition to electron-deficient olefins, establishing the selective allylic C-H alkylation of enol silyl ethers. This strategy is broadly applicable, and the alkylated enol silyl ethers can be transformed into highly functionalized carbonyl compounds by exploiting their common polar reactivity.

| S-EPMC6586846 | biostudies-literature

Selective Synthesis of <i>Z</i>-Silyl Enol Ethers via Ni-Catalyzed Remote Functionalization of Ketones.

Project description:We report a remote functionalization strategy, which allows the Z-selective synthesis of silyl enol ethers of (hetero)aromatic and aliphatic ketones via Ni-catalyzed chain walking from a distant olefin site. The positional selectivity is controlled by the directionality of the chain walk and is independent of thermodynamic preferences of the resulting silyl enol ether. Our mechanistic data indicate that a Ni(I) dimer is formed under these conditions, which serves as a catalyst resting state and, upon reaction with an alkyl bromide, is converted to [Ni(II)-H] as an active chain-walking/functionalization catalyst, ultimately generating a stabilized η3-bound Ni(II) enolate as the key selectivity-controlling intermediate.

| S-EPMC8193638 | 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