Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Diversification reactions of ?-silyl allenyl esters: selective conversion to all-carbon quaternary centers and ?-allene dicarbinols.

ABSTRACT: The unique reactivity of ?-silyl allenyl esters is described. Taking advantage of the silyl group as a fluoride acceptor, these allenoates readily underwent addition to a variety of electrophiles to selectively yield products with all-carbon quaternary centers or allenoate dicarbinols. These dicarbinols were subsequently converted to novel highly substituted 6-hydro-2-pyrones.

SUBMITTER: Jana S

PROVIDER: S-EPMC5510162 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Diversification reactions of γ-silyl allenyl esters: selective conversion to all-carbon quaternary centers and γ-allene dicarbinols.

Jana Susovan S Roy Animesh A Lepore Salvatore D SD

Chemical communications (Cambridge, England) 20170501 37

The unique reactivity of γ-silyl allenyl esters is described. Taking advantage of the silyl group as a fluoride acceptor, these allenoates readily underwent addition to a variety of electrophiles to selectively yield products with all-carbon quaternary centers or allenoate dicarbinols. These dicarbinols were subsequently converted to novel highly substituted 6-hydro-2-pyrones. ...[more]

PMID: 28435948

Similar Datasets

Annulation reactions of allenyl esters: an approach to bicyclic diones and medium-sized rings.

Project description:A flexible approach to construct sterically congested bicyclo-alkenedione frameworks is reported. Under the action of potassium carbonate, α-sulphonyl cycloalkanones are added to functionalized allenyl esters, leading to a lactone intermediate that is subsequently reduced to initiate an intramolecular aldol cyclization to [3.2.1], [3.3.1], and [4.3.1] bicycles. Oxidation then affords bicyclic diones in good three-step yields. Under exceptionally mild conditions, these bicycles are converted to highly functionalized medium-sized rings through a Grob-type fragmentation.

| S-EPMC4184455 | biostudies-literature

Palladium-catalyzed gamma-arylation of alpha,beta-unsaturated esters from silyl ketene acetals.

Project description: Not available

| S-EPMC3159490 | biostudies-literature

Stereocontrolled Access to Quaternary Centers by Birch Reduction/Alkylation of Chiral Esters of Salicylic Acids.

Project description:8-Phenylmenthol esters of salicylic acid derivatives undergo efficient Birch reduction and in situ diastereoselective alkylations to afford methoxycyclohexadienes bearing new quaternary stereogenic centers. The use of an ester-based auxiliary is a designed improvement over the use of prolinol-derived amides, which are expensive and often very difficult to cleave.

| S-EPMC10167686 | biostudies-literature

Site- and enantioselective formation of allene-bearing tertiary or quaternary carbon stereogenic centers through NHC-Cu-catalyzed allylic substitution.

Project description:Catalytic enantioselective allylic substitutions that result in addition of an allenyl group (<2% propargyl addition) and formation of tertiary or quaternary C-C bonds are described. Commercially available allenylboronic acid pinacol ester is used. Reactions are promoted by a 5.0-10 mol % loading of sulfonate-bearing chiral bidentate N-heterocyclic carbene (NHC) complexes of copper, which exhibit the unique ability to furnish chiral products arising from the S(N)2' mode of addition. Allenyl-containing products are generated in up to 95% yield, >98% S(N)2' selectivity, and 99:1 enantiomeric ratio (er). Site-selective NHC-Cu-catalyzed hydroboration of enantiomerically enriched allenes and conversion to the corresponding β-vinyl ketones demonstrates the method's utility.

| S-EPMC3267425 | biostudies-literature

Synthesis of aza-quaternary centers <i>via</i> Pictet-Spengler reactions of ketonitrones.

Project description:Despite the array of advances that have been made in Pictet-Spengler chemistry, particularly as it relates to the synthesis of β-carboline derivatives of both natural and designed origin, the ability to use such reactions to generate aza-quaternary centers remains limited. Herein, we report a simple procedure that enables the synthesis of a variety of such products by harnessing the distinct reactivity profiles of ketonitrones as activated by commercially available acyl chlorides. Notably, the reaction process is mild, fast, and high-yielding (54-97%) for a diverse collection of substrates, including some typically challenging ones, such as indole cores with electron-deficient substituents. In addition, by deploying an acyl bromide in combination with a thiourea promoter, a catalytic, asymmetric version has been established, leading to good levels of enantioselectivity (up to 83% ee) for several ketonitrones. Finally, the resultant N-O bonds within the products can also be functionalized in several unique ways, affording valuable complementarity to existing Pictet-Spengler variants based on the use of imines.

| S-EPMC8098696 | biostudies-literature

Allenoate Prenucleophiles: A Triply Diastereoselective Approach to β-Hydroxy Esters Containing All-Carbon α-Quaternary Centers.

Project description:Allenyl esters activated by titanium(IV) underwent additions to a wide range of aldehydes in high regio- and diastereoselectivities leading to products containing an all-carbon quaternary center bearing an α-vinyl group that was installed with high selectivity for the Z-geometry. An aldol product was also converted to an indanone offering a new route to this important compound class. Product triple diastereoselectivity has been rationalized using a concerted transition-state model.

| S-EPMC9360042 | biostudies-literature

H-Bond Mediated Phase-Transfer Catalysis: Enantioselective Generating of Quaternary Stereogenic Centers in β-Keto Esters.

Project description:In this work, we would like to present the development of a highly optimized method for generating the quaternary stereogenic centers in β-keto esters. This enantioselective phase-transfer alkylation catalyzed by hybrid Cinchona catalysts allows for the efficient generation of the optically active products with excellent enantioselectivity, using only 1 mol% of the catalyst. The vast majority of phase-transfer catalysts in asymmetric synthesis work by creating ionic pairs with the nucleophile-attacking anionic substrate. Therefore, it is a sensible approach to search for new methodologies capable of introducing functional groups into the precursor's structure, maintaining high yields and enantiomeric purity.

| S-EPMC9024675 | biostudies-literature

Allenyl esters as quenching agents for ruthenium olefin metathesis catalysts.

Project description:In the attempt to synthesize substituted allenyl esters through a metathesis coupling of unsubstituted allenyl esters and alkenes using a variety of ruthenium catalysts, it was discovered that allenyl esters themselves cleanly arrested the activity of the catalysts. Further studies suggests possible utility of allene esters as general quenching agents for metathesis reactions. To explore this idea, several representative olefin metathesis reactions, including ring closing, were successfully terminated by the addition of simple allenyl esters for more convenient purification.

| S-EPMC5475365 | biostudies-literature

Ligand-enabled γ-C-H olefination and carbonylation: construction of β-quaternary carbon centers.

Project description:Monoselective γ-C-H olefination and carbonylation of aliphatic acids has been accomplished by using a combination of a quinoline-based ligand and a weakly coordinating amide directing group. The reaction provides a new route for constructing richly functionalized all-carbon quaternary carbon centers at the β-position of aliphatic acids.

| S-EPMC4049142 | biostudies-literature

Highly enantioselective, intermolecular hydroamination of allenyl esters catalyzed by bifunctional phosphinothioureas.

Project description:Bifunctional phosphinothiourea catalysts have been developed successfully for the highly regio- and enantioselective γ-hydroamination of allenyl and propargyl esters with N-methoxy carbamate nucleophiles to yield α,β-unsaturated γ-amino acid ester products. In the case of propargyl ester substrates, the reaction proceeds through reversible phosphinothiourea-catalyzed isomerization to the corresponding allenyl ester. The high enantioselectivity of the process is attributed to a cooperative conjugate addition of a thiourea-bound carbamate anion to a vinyl phosphonium ion resulting from covalent activation of the allenyl ester substrate.

| S-EPMC4291748 | 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