Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones.

ABSTRACT: Thiazolium carbene-catalyzed reactions of 1,2-diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave ?,?-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products.

SUBMITTER: Takaki K

PROVIDER: S-EPMC5588593 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones.

Takaki Ken K Hino Makoto M Ohno Akira A Komeyama Kimihiro K Yoshida Hiroto H Fukuoka Hiroshi H

Beilstein journal of organic chemistry 20170830

Thiazolium carbene-catalyzed reactions of 1,2-diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave α,β-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products. ...[more]

PMID: 28904625

Similar Datasets

Synthesis of Indolyl Phenyl Diketones through Visible-Light-Promoted Ni-Catalyzed Intramolecular Cyclization/Oxidation Sequence of Ynones

Project description: Not available

| S-EPMC10995934 | biostudies-literature

Gold-catalyzed 1,3-transposition of ynones.

Project description:An efficient, regioselective gold-catalyzed 1,3-transposition reaction of ynones and diynones has been developed. It was found that stereoelectronic (interrupted conjugation) and electronic (extended conjugation) factors could efficiently govern the regioselectivity of this thermodynamically controlled transformation. The produced conjugated diynones were efficiently transformed into diverse alkyne-substituted five- and six-membered heterocycles.

| S-EPMC4206192 | biostudies-literature

Vicinal diboronates in high enantiomeric purity through tandem site-selective NHC-Cu-catalyzed boron-copper additions to terminal alkynes.

Project description:A Cu-catalyzed protocol for conversion of terminal alkynes to enantiomerically enriched diboronates is reported. In a single vessel, a site-selective hydroboration of an alkyne leads to the corresponding terminal vinylboronate, which undergoes a second site-selective and enantioselective hydroboration. Reactions proceed in the presence of 2 equiv of commercially available bis(pinacolato)diboron [B(2)(pin)(2)] and 5-7.5 mol % loading of a chiral bidentate imidazolinium salt, affording diboronates in 60-93% yield and up to 97.5:2.5 enantiomeric ratio (er). The enantiomerically enriched products can be functionalized to afford an assortment of versatile organic molecules. Enynes are converted to unsaturated diboronates with high chemo- (>98% reaction of alkyne; <2% at alkene) and enantioselectivity (e.g., 94.5:5.5 er).

| S-EPMC2797564 | biostudies-literature

Ni(NHC)]-catalyzed cycloaddition of diynes and tropone: apparent enone cycloaddition involving an 8? insertion.

Project description:A Ni/N-heterocyclic carbene catalyst couples diynes to the C(?)-C(?) double bond of tropone, a type of reaction that is unprecedented for metal-catalyzed cycloadditions with aromatic tropone. Many different diynes were efficiently coupled to afford [5-6-7] fused tricyclic products, while [5-7-6] fused tricyclic compounds were obtained as minor byproducts in a few cases. The reaction has broad substrate scope and tolerates a wide range of functional groups, and excellent regioselectivity is found with unsymmetrical diynes. Theoretical calculations show that the apparent enone cycloaddition occurs through a distinctive 8? insertion of tropone. The initial intramolecular oxidative cyclization of diyne produces the nickelacyclopentadiene intermediate. This intermediate undergoes an 8? insertion of tropone, and subsequent reductive elimination generates the [5-6-7] fused tricyclic product. This initial product undergoes two competing isomerizations, leading to the observed [5-6-7] and [5-7-6] fused tricyclic products.

| S-EPMC4291811 | biostudies-other

Enantioselective synthesis of boron-substituted quaternary carbon stereogenic centers through NHC-catalyzed conjugate additions of (pinacolato)boron units to enones.

Project description:The first examples of Lewis base catalyzed enantioselective boryl conjugate additions (BCAs) that generate products containing boron-substituted quaternary carbon stereogenic centers are disclosed. Reactions are performed in the presence of 1.0-5.0?mol% of a readily accessible chiral accessible N-heterocyclic carbene (NHC) and commercially available bis(pinacolato)diboron; cyclic or linear ?,?-unsaturated ketones can be used and rigorous exclusion of air or moisture is not necessary. The desired products are obtained in 63-95% yield and 91:9 to >99:1 enantiomeric ratio (e.r.). The special utility of the NHC-catalyzed approach is demonstrated in the context of an enantioselective synthesis of natural product antifungal (-)-crassinervic acid.

| S-EPMC4094110 | biostudies-literature

Coligand role in the NHC nickel catalyzed C-F bond activation: investigations on the insertion of bis(NHC) nickel into the C-F bond of hexafluorobenzene.

Project description:The reaction of [Ni(Mes2Im)2] (1) (Mes2Im = 1,3-dimesityl-imidazolin-2-ylidene) with polyfluorinated arenes as well as mechanistic investigations concerning the insertion of 1 and [Ni(iPr2Im)2] (1ipr) (iPr2Im = 1,3-diisopropyl-imidazolin-2-ylidene) into the C-F bond of C6F6 is reported. The reaction of 1 with different fluoroaromatics leads to formation of the nickel fluoroaryl fluoride complexes trans-[Ni(Mes2Im)2(F)(ArF)] (ArF = 4-CF3-C6F4 2, C6F5 3, 2,3,5,6-C6F4N 4, 2,3,5,6-C6F4H 5, 2,3,5-C6F3H2 6, 3,5-C6F2H3 7) in fair to good yields with the exception of the formation of the pentafluorophenyl complex 3 (less than 20%). Radical species and other diamagnetic side products were detected for the reaction of 1 with C6F6, in line with a radical pathway for the C-F bond activation step using 1. The difluoride complex trans-[Ni(Mes2Im)2(F)2] (9), the bis(aryl) complex trans-[Ni(Mes2Im)2(C6F5)2] (15), the structurally characterized nickel(i) complex trans-[NiI(Mes2Im)2(C6F5)] (11) and the metal radical trans-[NiI(Mes2Im)2(F)] (12) were identified. Complex 11, and related [NiI(Mes2Im)2(2,3,5,6-C6F4H)] (13) and [NiI(Mes2Im)2(2,3,5-C6F3H2)] (14), were synthesized independently by reaction of trans-[Ni(Mes2Im)2(F)(ArF)] with PhSiH3. Simple electron transfer from 1 to C6F6 was excluded, as the redox potentials of the reaction partners do not match and [Ni(Mes2Im)2]+, which was prepared independently, was not detected. DFT calculations were performed on the insertion of [Ni(iPr2Im)2] (1ipr) and [Ni(Mes2Im)2] (1) into the C-F bond of C6F6. For 1ipr, concerted and NHC-assisted pathways were identified as having the lowest kinetic barriers, whereas for 1, a radical mechanism with fluoride abstraction and an NHC-assisted pathway are both associated with almost the same kinetic barrier.

| S-EPMC8162383 | biostudies-literature

Asymmetric Ni-catalyzed conjugate allylation of activated enones.

Project description:The nickel-catalyzed enantioselective addition of allylboronic acid pinacol ester, allylB(pin), is described. This reaction is highly effective with dialkylidene ketones and favors the allylation of the benzylidene site in nonsymmetric substrates. The reaction appears to proceed by conversion of the dialkylidene ketone substrate to an unsaturated pi-allyl complex (I), followed by reductive elimination. Enantioselectivities range from 91 to 94% ee for a range of substrates when chiral ligand 14 is employed.

| S-EPMC3065355 | biostudies-literature

A Ruthenium-Catalyzed Coupling of Alkynes with 1,3-Diketones.

Project description:Ruthenium(III) chloride hydrate is a convenient catalyst for the addition of active methylene compounds to aryl alkynes. These reactions are rapid, operationally simple, and high yielding in cases. Most significantly, no precautions are required to exclude air or water from the reactions. All reagents are commercially available at reasonable prices, and the reactions can be conducted in disposable glassware with minimal solvent.

| S-EPMC3423983 | biostudies-literature

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

Iron-catalyzed asymmetric epoxidation of β,β-disubstituted enones.

Project description:The combination of Fe(OTf)(2) and novel phenanthroline ligands enables the catalytic asymmetric epoxidation of acyclic β,β-disubstituted enones, which have been a heretofore inaccessible substrate class. The reaction provides highly enantioenriched α,β-epoxyketones (up to 92% ee) that can be further converted to functionalized β-ketoaldehydes with an all-carbon quaternary center.

| S-EPMC3116448 | 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