Browse
Submit Data
Databases
API
Help

Dataset Information

17 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

DBU-Mediated Addition of ?-Nitroketones to ?-Cyano-enones and ?,?-Unsaturated ?-Ketoesters: Synthesis of Dihydrofurans and Conjugated Dienes.

ABSTRACT: 1,8-Diazabicyclo[5.4.0]undec-7-ene-mediated reactions of ?-nitroketones with ?-cyano-enones and ?,?-unsaturated ?-ketoesters have been developed. The products, namely, dihydrofurans and conjugated dienes, were isolated in moderate to good yields, and a range of substitutions were tolerated.

SUBMITTER: Sahoo SC

PROVIDER: S-EPMC6648157 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

DBU-Mediated Addition of α-Nitroketones to α-Cyano-enones and α,β-Unsaturated α-Ketoesters: Synthesis of Dihydrofurans and Conjugated Dienes.

Sahoo Subas Chandra SC Maity Rajendra R Pan Subhas Chandra SC

ACS omega 20190206 2

1,8-Diazabicyclo[5.4.0]undec-7-ene-mediated reactions of α-nitroketones with α-cyano-enones and α,β-unsaturated α-ketoesters have been developed. The products, namely, dihydrofurans and conjugated dienes, were isolated in moderate to good yields, and a range of substitutions were tolerated. ...[more]

PMID: 31459511

Similar Datasets

Electrophilic reactivities of cyclic enones and α,β-unsaturated lactones.

Project description:The reactivities of cyclic enones and α,β-unsaturated lactones were characterized by following the kinetics of their reactions with colored carbon-centered reference nucleophiles in DMSO at 20 °C. The experimentally determined second-order rate constants k 2 were analyzed with the Mayr-Patz equation, lg k = s N(N + E), to furnish the electrophilicity descriptors E for the Michael acceptors. Cyclic enones and lactones show different reactivity trends than their acyclic analogs. While cyclization reduces the reactivity of enones slightly, α,β-unsaturated lactones are significantly more reactive Michael acceptors than analogously substituted open-chain esters. The observed reactivity trends were rationalized through quantum-chemically calculated Gibbs energy profiles (at the SMD(DMSO)/M06-2X/6-31+G(d,p) level of theory) and distortion interaction analysis for the reactions of the cyclic Michael acceptors with a sulfonium ylide. The electrophilicities of simplified electrophilic fragments reflect the general reactivity pattern of structurally more complex terpene-derived cyclic enones and sesquiterpene lactones, such as parthenolide.

| S-EPMC8179571 | biostudies-literature

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

Project description: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.

| S-EPMC2694574 | 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

Enantioselective Michael Addition of Cyclic β-Diones to α,β-Unsaturated Enones Catalyzed by Quinine-Based Organocatalysts.

Project description:An enantioselective (52-98% ee) Michael addition between cyclic β-diones and α,β-unsaturated enones was established in the presence of quinine-based primary amine or squaramide. A variety of cinnamones were smoothly converted into the desired 3,4-dihydropyrans in moderate to high yields (63-99%). Chalcones were also suitable acceptors and gave rise to the expected adducts in satisfactory yields (31-99%). The resulting adducts readily underwent further modification to form fused 4H-pyran or 2,3-dihydrofuran.

| S-EPMC6152274 | biostudies-literature

Catalytic enantioselective allene-anhydride approach to β,γ-unsaturated enones bearing an α-all-carbon-quarternary center.

Project description:A protocol of highly regio- and enantioselective copper-catalyzed hydroacylation of the non-terminal C[double bond, length as m-dash]C bond in 1,1-disubstituted terminal allenes with anhydrides has been developed. Both aromatic and aliphatic carboxylic anhydrides are applicable to the efficient construction of all carbon quarternary centers connected with a versatile C[double bond, length as m-dash]C bond and a useful ketone functionality. The synthetic potentials of the enantioenriched products have also been demonstrated. Density functional theory (DFT) calculations were performed to explain the steric outcome of the products: the hydroacylation proceeds through a six-membered transition state and the ligand-substrate steric interactions account for the observed enantioselectivity although the chiral ligand is far away from the to-be-genetated chiral center.

| S-EPMC8161143 | biostudies-literature

Selective α,δ-hydrocarboxylation of conjugated dienes utilizing CO<sub>2</sub> and electrosynthesis.

Project description:To date the majority of diene carboxylation processes afford the α,δ-dicarboxylated product, the selective mono-carboxylation of dienes is a significant challenge and the major product reported under transition metal catalysis arises from carboxylation at the α-carbon. Herein we report a new electrosynthetic approach, that does not rely on a sacrificial electrode, the reported method allows unprecedented direct access to carboxylic acids derived from dienes at the δ-position. In addition, the α,δ-dicarboxylic acid or the α,δ-reduced alkene can be easily accessed by simple modification of the reaction conditions.

| S-EPMC8163448 | 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

Anionic four-electron donor-based palladacycles as catalysts for addition reactions of arylboronic acids with alpha,beta-unsaturated ketones, aldehydes, and alpha-ketoesters.

Project description:Anionic four-electron donor-based palladacycle-catalyzed 1,4-additions of arylboronic acids with alpha,beta-unsaturated ketones and 1,2-additions of arylboronic acids with aldehydes and alpha-ketoesters are described. Our study demonstrated that palladacycles were highly efficient, practical catalysts for these addition reactions. The work described here not only opened a new paradigm for the application of palladacycles, but may also pave the road for other metalacycles as practically useful catalysts for such addition reactions including asymmetric ones. [reaction: see text].

| S-EPMC2597418 | biostudies-literature

Cobalt-catalyzed regioselective stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes.

Project description:We report the first stereoconvergent Markovnikov 1,2-hydrosilylation of conjugated dienes using catalysts generated from bench-stable Co(acac)2 and phosphine ligands. A wide range of E/Z-dienes underwent this Markovnikov 1,2-hydrosilylation in a stereoconvergent manner, affording (E)-allylsilanes in high isolated yields with high stereoselectivities (E/Z = >99?:?1) and high regioselectivities (b/l up to > 99?:?1). Mechanistic studies revealed that this stereoconvergence stems from a ?-?-? isomerization of an allylcobalt species generated by the 1,4-hydrometalation of Z-dienes. In addition, a cobalt catalyst that can only catalyze the hydrosilylation of the E-isomer of an (E/Z)-diene was identified, which allows the separation of the (Z)-isomer from an isomeric mixture of (E/Z)-dienes. Furthermore, asymmetric hydrosilylation of (E)-1-aryl-1,3-dienes was studied with Co(acac)2/(R)-difluorphos and good enantioselectivities (er up to 90?:?10) were obtained.

| S-EPMC5873224 | biostudies-other

Highly Enantioselective Iridium-Catalyzed Hydrogenation of Conjugated Trisubstituted Enones.

Project description:Asymmetric hydrogenation of conjugated enones is one of the most efficient and straightforward methods to prepare optically active ketones. In this study, chiral bidentate Ir-N,P complexes were utilized to access these scaffolds for ketones bearing the stereogenic center at both the α- and β-positions. Excellent enantiomeric excesses, of up to 99%, were obtained, accompanied with good to high isolated yields. Challenging dialkyl substituted substrates, which are difficult to hydrogenate with satisfactory chiral induction, were hydrogenated in a highly enantioselective fashion.

| S-EPMC7884017 | 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