Browse
Submit Data
Databases
API
Help

Dataset Information

33 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Copper-catalyzed enantioselective additions to oxocarbenium ions: alkynylation of isochroman acetals.

ABSTRACT: We have developed an enantioselective, copper(I)-catalyzed addition of terminal alkynes to racemic isochroman acetals. This method is one of the first transition-metal-catalyzed approaches to enantioselective additions to prochiral oxocarbenium ions. In this reaction, TMSOTf is used to form the oxocarbenium ion in situ under conditions compatible with simultaneous formation of the chiral copper acetylide. By using a bis(oxazoline) ligand, good yields and enantioselectivities are observed for a variety of enantioenriched 1-alkynyl isochromans.

SUBMITTER: Maity P

PROVIDER: S-EPMC4203715 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Copper-catalyzed enantioselective additions to oxocarbenium ions: alkynylation of isochroman acetals.

Maity Prantik P Srinivas Harathi D HD Watson Mary P MP

Journal of the American Chemical Society 20111011 43

We have developed an enantioselective, copper(I)-catalyzed addition of terminal alkynes to racemic isochroman acetals. This method is one of the first transition-metal-catalyzed approaches to enantioselective additions to prochiral oxocarbenium ions. In this reaction, TMSOTf is used to form the oxocarbenium ion in situ under conditions compatible with simultaneous formation of the chiral copper acetylide. By using a bis(oxazoline) ligand, good yields and enantioselectivities are observed for a v ...[more]

PMID: 21988178

Similar Datasets

Enantioselective copper-catalyzed alkynylation of benzopyranyl oxocarbenium ions.

Project description:We have developed highly enantioselective, copper-catalyzed alkynylations of benzopyranyl acetals. By using a copper(I) catalyst equipped with a chiral bis(oxazoline) ligand, high yields and enantioselectivities are achieved in the alkynylation of widely available, racemic isochroman and chromene acetals to deliver ?-chiral oxygen heterocycles. This method demonstrates that chiral organometallic nucleophiles can be successfully used in enantioselective additions to oxocarbenium ions.

| S-EPMC4822504 | biostudies-literature

Enantioselective thiourea-catalyzed additions to oxocarbenium ions.

Project description:Asymmetric, catalytic reactions of oxocarbenium ions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbenium ion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest enantioselectivities, with the optimal structure being derived from enantioenriched 2-arylpyrrolidine derivatives.

| S-EPMC2574628 | biostudies-literature

Enantioselective Copper(I)-Catalyzed Alkynylation of Oxocarbenium Ions to Set Diaryl Tetrasubstituted Stereocenters.

Project description:An enantioselective, copper(I)-catalyzed addition of terminal alkynes to isochroman ketals to set diaryl, tetrasubstituted stereocenters has been developed. The success of this reaction relies on identification of a Cu/PyBox catalyst capable of distinguishing the faces of the diaryl-substituted oxocarbenium ion. This challenging transformation enables efficient conversion of readily available, racemic ketals into high-value enantioenriched isochroman products with fully substituted stereogenic centers. High yields and enantiomeric excesses are observed for various isochroman ketals and an array of alkynes.

| S-EPMC4819992 | biostudies-literature

Copper Bis(oxazoline)-Catalyzed Enantioselective Alkynylation of Benzopyrylium Ions.

Project description:The stereocontrolled construction of biologically relevant chromanones and tetrahydroxanthones has been achieved through the addition of alkynes to benzopyrylium trilfates under the influence of copper bis(oxazoline) catalysis. Excellent levels of enantiocontrol (63-98 % ee) are achieved in the addition of a variety of alkynes to an array of chromenones with a hydrogen in the 2-position. Promising levels of enantiocontrol (54-67 % ee) are achieved in the alkynylation of chromenones with esters in the 2-position, generating tertiary ether stereocenters resembling those frequently found in naturally occurring metabolites.

| S-EPMC7262874 | biostudies-literature

Diastereoselective, Zinc-Catalyzed Alkynylation of ?-Bromo Oxocarbenium Ions.

Project description:We have developed a bromination/alkynylation sequence that enables efficient transformation of simple cyclic enol ethers to difunctionalized products. The success of this strategy relies on a highly diastereselective, zinc-catalyzed addition of terminal alkynes to ?-bromo oxocarbenium ions, formed in situ via ionization of acetal precursors. Using this method, trans-?-alkynyl-?-halo pyran and furan derivatives can be prepared with high diastereoselectivity and excellent functional group tolerance.

| S-EPMC4820761 | biostudies-literature

Enantioselective, Copper-Catalyzed Alkynylation of Ketimines To Deliver Isoquinolines with ?-Diaryl Tetrasubstituted Stereocenters.

Project description:An enantioselective, copper-catalyzed alkynylation of cyclic ?,?-diaryl ketiminium ions has been developed to deliver isoquinoline products with diaryl, tetrasubstituted stereocenters. The success of this reaction relied on identification of Ph-PyBox as the optimal ligand, i-Pr2NEt as the base, and CHCl3 as the solvent. A broad scope and functional group tolerance were observed. Notably, the use of both aryl and silyl acetylenes results in high yields and enantioselectivities. Mechanistic experiments are consistent with a dimeric or higher order catalyst.

| S-EPMC5161116 | biostudies-literature

Enantioselective Alkynylation of Unstabilized Cyclic Iminium Ions.

Project description:An enantioselective copper-catalyzed alkynylation of unstabilized cyclic iminium ions has been developed. Whereas such alkynylations typically utilize pyridinium, quinolinium and isoquinolinium intermediates, this method enables use of cyclic iminium ions unstabilized by resonance. With the use of a Lewis acid and copper catalyst, these iminium ions are generated in situ from readily available hemiaminal methyl ethers and transformed into highly enantioenriched α-alkynylated cyclic amines. A variety of terminal alkynes can be incorporated in high yields and enantiomeric excesses.

| S-EPMC10769448 | biostudies-literature

Calcium(ii)-catalyzed enantioselective conjugate additions of amines.

Project description:The direct enantioselective chiral calcium(ii)·phosphate complex (Ca[CPA]2)-catalyzed conjugate addition of unprotected alkyl amines to maleimides was developed. This mild catalytic system represents a significant advance towards the general convergent asymmetric amination of ?,?-unsaturated electrophiles, providing medicinally relevant chiral aminosuccinimide products in high yields and enantioselectivities. Furthermore, the catalyst can be reused directly from a previously chromatographed reaction and still maintain both high yield and selectivity.

| S-EPMC5887857 | biostudies-other

Asymmetric Induction via a Helically Chiral Anion: Enantioselective Pentacarboxycyclopentadiene Bronsted Acid-Catalyzed Inverse-Electron-Demand Diels-Alder Cycloaddition of Oxocarbenium Ions.

Project description:An enantioselective catalytic inverse-electron-demand Diels-Alder reaction of salicylaldehyde acetal-derived oxocarbenium ions and vinyl ethers to generate 2,4-dioxychromanes is described. Chiral pentacarboxycyclopentadiene (PCCP) acids are found to be effective for a variety of substrates. Computational and X-ray crystallographic analyses support the unique hypothesis that an anion with point-chirality-induced helical chirality dictates the absolute sense of stereochemistry in this reaction.

| S-EPMC5859540 | biostudies-literature

Highly Enantioselective, Hydrogen-Bond-Donor Catalyzed Additions to Oxetanes.

Project description:A precisely designed chiral squaramide derivative is shown to promote the highly enantioselective addition of trimethylsilyl bromide (TMSBr) to a broad variety of 3-substituted and 3,3-disubstituted oxetanes. The reaction provides direct and general access to synthetically valuable 1,3-bromohydrin building blocks from easily accessed achiral precursors. The products are readily elaborated both by nucleophilic substitution and through transition-metal-catalyzed cross-coupling reactions. The enantioselective catalytic oxetane ring opening was employed as part of a three-step, gram-scale synthesis of pretomanid, a recently approved medication for the treatment of multidrug-resistant tuberculosis. Heavy-atom kinetic isotope effect (KIE) studies are consistent with enantiodetermining delivery of bromide from the H-bond-donor (HBD) catalyst to the activated oxetane. While the nucleophilicity of the bromide ion is expected to be attenuated by association to the HBD, overall rate acceleration is achieved by enhancement of Lewis acidity of the TMSBr reagent through anion abstraction.

| S-EPMC7293824 | 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