Browse
Submit Data
Databases
API
Help

Dataset Information

57 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Catalytic, asymmetric Michael reactions of cyclic diketones with beta,gamma-unsaturated alpha-ketoesters.

ABSTRACT: Newly synthesized cinchona alkaloid-derived pyrimidines function as effective asymmetric catalysts for the Michael reaction between cyclic diketones and beta,gamma-unsaturated alpha-ketoesters. The reactions of electrophiles with either aryl or alkyl gamma-substituents give 64-99% yields and 94-99% ee.

SUBMITTER: Calter MA

PROVIDER: S-EPMC2694574 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Catalytic, asymmetric Michael reactions of cyclic diketones with beta,gamma-unsaturated alpha-ketoesters.

Calter Michael A MA Wang Jun J

Organic letters 20090501 10

Newly synthesized cinchona alkaloid-derived pyrimidines function as effective asymmetric catalysts for the Michael reaction between cyclic diketones and beta,gamma-unsaturated alpha-ketoesters. The reactions of electrophiles with either aryl or alkyl gamma-substituents give 64-99% yields and 94-99% ee. ...[more]

PMID: 19366193

Similar Datasets

Direct Catalytic Asymmetric Doubly Vinylogous Michael Addition of α,β-Unsaturated γ-Butyrolactams to Dienones.

Project description:An asymmetric doubly vinylogous Michael addition (DVMA) of α,β-unsaturated γ-butyrolactams to sterically congested β-substituted cyclic dienones with high site-, diastereo-, and enantioselectivity has been achieved. An unprecedented DVMA/vinylogous Michael addition/isomerization cascade reaction affords chiral fused tricyclic γ-lactams with four newly formed stereocenters.

| S-EPMC4678421 | biostudies-literature

Asymmetric aza-Michael reactions of alpha,beta-unsaturated ketones with bifunctional organic catalysts.

Project description: Not available

| S-EPMC2652737 | biostudies-literature

Catalytic asymmetric addition of diphenylzinc to cyclic alpha,beta-unsaturated ketones.

Project description:We have examined the use of our bis(sulfonamide) diol ligand (1) in the asymmetric addition of phenyl groups to cyclic alpha,beta-unsaturated ketones. Good to excellent enantioselectivities have been obtained with cyclic enones bearing alkyl substituents in the 2 position (71-97% enantiomeric excess). Furthermore, excellent enantioselectivities have been observed in the asymmetric phenylation of cyclic enones with 2-iodo and 2-bromo substituents. The results of this study broaden the scope of the asymmetric additions to ketones promoted by the titanium catalyst derived from ligand 1.

| S-EPMC397398 | biostudies-literature

Trityl Cation-Catalyzed Hosomi-Sakurai Reaction of Allylsilane with β,γ-Unsaturated α-Ketoester to Form γ,γ-Disubstituted α-Ketoesters.

Project description:(Ph3C)[BPh(F)4]-catalyzed Hosomi-Sakurai allylation of allylsilanes with β,γ-unsaturated α-ketoesters has been developed to give γ,γ-disubstituted α-ketoesters in high yields with excellent chemoselectivity. Preliminary mechanistic studies suggest that trityl cation dominates the catalysis, while the silyl cation plays a minor role.

| S-EPMC9331905 | biostudies-literature

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones.

Project description:The organocatalytic Michael addition of malonates to symmetric unsaturated 1,4-diketones catalyzed by thiourea and squaramide derivatives with Cinchona alkaloids afforded the formation of a new C-C bond in high yields (up to 98%) and enantiomeric purities (up to 93%). The absolute configuration of the product was suggested from comparison of the experimental and calculated VCD spectra of the reaction product 3a.

| S-EPMC3458770 | biostudies-literature

Lewis acid-catalyzed asymmetric reactions of β,γ-unsaturated 2-acyl imidazoles.

Project description:The investigation of diverse reactivity of β,γ-unsaturated carbonyl compounds is of great value in asymmetric catalytic synthesis. Numerous enantioselective transformations have been well developed with β,γ-unsaturated carbonyl compounds as nucleophiles, however, few example were realized by utilizing them as not only nucleophiles but also electrophiles under a same catalytic system. Here we report a regioselective catalytic asymmetric tandem isomerization/α-Michael addition of β,γ-unsaturated 2-acyl imidazoles in the presence of chiral N,N'-dioxide metal complexes, delivering a broad range of optically pure 1,5-dicarbonyl compounds with two vicinal tertiary carbon stereocenters in up to >99% ee under mild conditions. Meanwhile, stereodivergent synthesis is disclosed to yield all four stereoisomers of products. Control experiments suggest an isomerization process involved in the reaction and give an insight into the role of NEt3. In addition, Mannich reaction and sulfur-Michael addition of β,γ-unsaturated 2-acyl imidazoles proceed smoothly as well under the same catalytic system.

| S-EPMC7398931 | biostudies-literature

Asymmetric hydrogenation of exocyclic γ,δ-unsaturated β-ketoesters to functionalized chiral allylic alcohols <i>via</i> dynamic kinetic resolution.

Project description:An iridium catalyzed asymmetric hydrogenation of racemic exocyclic γ,δ-unsaturated β-ketoesters via dynamic kinetic resolution to functionalized chiral allylic alcohols was developed. With the chiral spiro iridium catalysts Ir-SpiroPAP, a series of racemic exocyclic γ,δ-unsaturated β-ketoesters bearing a five-, six-, or seven-membered ring were hydrogenated to the corresponding functionalized chiral allylic alcohols in high yields with good to excellent enantioselectivities (87 to >99% ee) and cis-selectivities (93 : 7 to >99 : 1). The origin of the excellent stereoselectivity was also rationalized by density functional theory calculations. Furthermore, this protocol could be performed on gram scale and at a lower catalyst loading (0.002 mol%) without the loss of reactivity and enantioselectivity, and has been successfully applied in the enantioselective synthesis of chiral carbocyclic δ-amino esters and the β-galactosidase inhibitor isogalactofagomine.

| S-EPMC8188505 | biostudies-literature

Understanding divergent substrate stereoselectivity in the isothiourea-catalysed conjugate addition of cyclic α-substituted β-ketoesters to α,β-unsaturated aryl esters.

Project description:The development of enantioselective synthetic methods capable of generating vicinal stereogenic centres, where one is tetrasubstituted (such as either an all-carbon quaternary centre or where one or more substituents are heteroatoms), is a recognised synthetic challenge. Herein, the enantioselective conjugate addition of a range of carbo- and heterocyclic α-substituted β-ketoesters to α,β-unsaturated aryl esters using the isothiourea HyperBTM as a Lewis base catalyst is demonstrated. Notably, divergent diastereoselectivity is observed through the use of either cyclopentanone-derived or indanone-derived substituted β-ketoesters with both generating the desired stereodefined products with high selectivity (>95 : 5 dr, up to 99 : 1 er). The scope and limitations of these processes are demonstrated, alongside application on gram scale. The origin of the divergent substrate selectivity has been probed through the use of DFT-analysis, with preferential orientation driven by dual stabilising CH⋯O interactions. The importance of solvation with strongly polar transition-states is highlighted and the SMD solvation model is demonstrated to capture solvation effects reliably.

| S-EPMC10717594 | biostudies-literature

Enantiospecific deoxyfluorination of cyclic α-OH-β-ketoesters.

Project description:We herein report the deoxyfluorination of cyclic α-hydroxy-β-ketoesters using diethylaminosulfur trifluoride (DAST). The reaction proceeds with excellent levels of stereospecificity, giving the configurationally inverted α-fluoro-β-ketoesters in high yields under operationally simple conditions.

| S-EPMC7116657 | biostudies-literature

Asymmetric, organocatalytic, three-step synthesis of alpha-hydroxy-(E)-beta,gamma-unsaturated esters.

Project description:An efficient and enantiocontrolled three-step synthesis of alpha-hydroxy-(E)-beta,gamma-unsaturated esters is reported. Enantioenriched alpha-selenyl aldehydes, prepared in one step by asymmetric, organocatalytic alpha-selenylation of aldehydes, were directly subjected to a Wittig reaction followed by allylic selenide to selenoxide oxidation and final spontaneous [2,3]-sigmatropic rearrangement to yield the target compounds in 43-65% overall yield and in 94-97% ee.

| S-EPMC2864524 | 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