Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A reductive coupling strategy towards ripostatin A.

ABSTRACT: Synthetic studies on the antibiotic natural product ripostatin A have been carried out with the aim to construct the C9-C10 bond by a nickel(0)-catalyzed coupling reaction of an enyne and an epoxide, followed by rearrangement of the resulting dienylcyclopropane intermediate to afford the skipped 1,4,7-triene. A cyclopropyl enyne fragment corresponding to C1-C9 has been synthesized in high yield and demonstrated to be a competent substrate for the nickel(0)-catalyzed coupling with a model epoxide. Several synthetic approaches toward the C10-C26 epoxide have been pursued. The C13 stereocenter can be set by allylation and reductive decyanation of a cyanohydrin acetonide. A mild, fluoride-promoted decarboxylation enables construction of the C15-C16 bond by an aldol reaction. The product of this transformation is of the correct oxidation state and potentially three steps removed from the targeted epoxide fragment.

SUBMITTER: Schleicher KD

PROVIDER: S-EPMC3740708 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

A reductive coupling strategy towards ripostatin A.

Schleicher Kristin D KD Jamison Timothy F TF

Beilstein journal of organic chemistry 20130731

Synthetic studies on the antibiotic natural product ripostatin A have been carried out with the aim to construct the C9-C10 bond by a nickel(0)-catalyzed coupling reaction of an enyne and an epoxide, followed by rearrangement of the resulting dienylcyclopropane intermediate to afford the skipped 1,4,7-triene. A cyclopropyl enyne fragment corresponding to C1-C9 has been synthesized in high yield and demonstrated to be a competent substrate for the nickel(0)-catalyzed coupling with a model epoxide ...[more]

PMID: 23946853

Similar Datasets

Efficient preparation of unsymmetrical disulfides by nickel-catalyzed reductive coupling strategy.

Project description:Disulfides are widely found in natural products and find a wide range of applications in life sciences, materials chemistry and other fields. The preparation of disulfides mainly rely on oxidative couplings of two sulfur containing compounds. This strategy has many side reactions and other shortcomings. Herein, we describe the reductive nickel-catalyzed cross-electrophile coupling of unactivated alkyl bromides with symmetrical alkyl- and aryltetrasulfides to form alkyl-alkyl and aryl-alkyl unsymmetrical disulfides. This approach for disulfide synthesis is practical, relies on easily available, unfunctionalized substrates, and is scalable. We investigated the mechanism of this transformation and found that the tetrasulfide compound does not selectively break the central S-S bond, but regio-selectively generates trisulfide intermediates.

| S-EPMC9095708 | biostudies-literature

Reductive Coupling of Acrylates with Ketones and Ketimines by a Nickel-Catalyzed Transfer-Hydrogenative Strategy.

Project description:Nickel-catalyzed coupling of benzyl acrylates with activated ketones and imines provides ?-butyrolactones and lactams, respectively. The benzyl alcohol byproduct released during the lactonization/lactamization event is relayed to the next cycle where it serves as the reductant for C-C bond formation. This strategy represents a conceptually unique approach to transfer-hydrogenative C-C bond formation, thus providing examples of reductive heterocyclizations where hydrogen embedded within an alcohol leaving group facilitates turnover.

| S-EPMC5656909 | biostudies-literature

Nickel-Catalyzed Asymmetric Domino Ring Opening/Cross-Coupling Reaction of Cyclobutanones via a Reductive Strategy.

Project description:Herein we demonstrate the successful application of reductive strategy in the asymmetric domino ring opening/cross-coupling reaction of prochiral cyclobutanones. Under the catalysis of a chiral nickel complex, various aryl iodide-tethered cyclobutanones were reacted with alkyl bromides as the electrophilic coupling partner, providing a variety of chiral indanones bearing a quaternary stereogenic center in highly enantioselective manner, which can be further converted to diverse benzene-fused cyclic compounds including indane, indene, dihydrocoumarin, and dihydroquinolinone. The preliminary mechanistic investigations support a mechanism involving Ni(I)-mediated enantiotopic C-C σ-bond activation of cyclobutanones as key elementary step in the catalytic cycle.

| S-EPMC7155205 | biostudies-literature

A practical and catalytic reductive olefin coupling.

Project description:A redox-economic method for the direct coupling of olefins that uses an inexpensive iron catalyst and a silane reducing agent is reported. Thus, unactivated olefins can be joined directly to electron-deficient olefins in both intra- and intermolecular settings to generate hindered bicyclic systems, vicinal quaternary centers, and even cyclopropanes in good yield. The reaction is not sensitive to oxygen or moisture and has been performed on gram-scale. Most importantly, it allows access to many compounds that would be difficult or perhaps impossible to access using other methods.

| S-EPMC3971728 | biostudies-literature

Phosphite-Mediated Reductive Cross-Coupling of Isatins and Nitrostyrenes.

Project description:A new reductive coupling reaction between N-alkylisatins, dimethyl phosphite, and nitrostyrenes has been developed. The reaction relies on Pudovik addition, subsequent phosphonate-phosphate rearrangement, and Michael-type addition of a transient carbanion on the indolinone with β-nitrostyrenes. This protocol introduces a convenient and versatile method for the construction of polyfunctionalized tertiary phosphates under mild conditions. Chiral general bases catalyze the title reaction with promising levels of enantioselectivity.

| S-EPMC8278291 | biostudies-literature

Enantioselective reductive multicomponent coupling reactions between isatins and aldehydes.

Project description:A metal-free stereoselective reductive coupling reaction between isatins and aldehydes is reported. The reaction relies on commercial diethyl phosphite (∼€70 kg-1) as the stoichiometric reductant. Base-catalyzed Pudovik addition and phosphonate/phosphate rearrangement achieved polarity inversion on the isatin, and the derived carbanions were trapped by aldehydes with subsequent dialkoxyphosphinyl migration. Chiral iminophosphoranes were used as basic catalysts to achieve high diastereo- and enantioselectivities with excellent yields.

| S-EPMC4618493 | biostudies-literature

Copper-catalysed asymmetric reductive cross-coupling of prochiral alkenes.

Project description:Asymmetric construction of C(sp3)-C(sp3) bond with good stereocontrol of the two connecting carbon centres retaining all carbon or hydrogen substituents is a challenging target in transition metal catalysis. Transition metal-catalysed reductive coupling of unsaturated π-substrates is considered as a potent tool to expediently develop the molecular complexity with high atom efficiency. However, such an asymmetric and intermolecular process has yet to be developed fully. Herein, we report an efficient strategy to reductively couple two prochiral conjugate alkenes using a copper-catalysed tandem protocol in the presence of diboron. Notably, this transformation incorporates a wide range of terminal and internal enynes as coupling partners and facilitates highly diastereo- and enantioselective synthesis of organoboron derivatives with multiple adjacent stereocentres in a single operation.

| S-EPMC9095606 | biostudies-literature

Asymmetric Organocatalytic Reductive Coupling Reactions between Benzylidene Pyruvates and Aldehydes.

Project description:An organocatalytic three-component reductive coupling reaction between dimethyl phosphite, benzylidene pyruvates, and aldehydes is reported. A chiral triaryliminophosphorane catalyst promotes Pudovik addition, which is followed by phospha-Brook rearrangement to transiently generate enolates that are trapped stereoselectively by aldehydes. This reductive coupling provides vicinal polyfunctionalized stereocenters from readily available prochiral starting materials with excellent diastereoselectivity, enantioselectivity, and yield.

| S-EPMC4701628 | biostudies-literature

Heme-copper assembly mediated reductive coupling of nitrogen monoxide (*NO).

Project description:A iron-dinitrosyl species ((6)L)Fe(NO)(2) (2), generated from nitrogen monoxide (*NO) binding to its related iron(II)-mononitrosyl complex ((6)L)Fe(NO) (1), efficiently effects reductive coupling of two *NO molecules to release nitrous oxide (N(2)O), when Cu(+) ion and 2 equiv acid are added; the heme/Cu product is [((6)L)Fe(III)...Cu(II)(D)](3+) (D = H(2)O or MeCN). In a control experiment where only ((6)L)Fe(NO)(2) (2) is exposed to 2 equiv acid, no UV-vis change is observed; upon warming, *NO((g)) is released and ((6)L)Fe(NO) is reformed. The copper ion complex within the (6)L ligand framework is required for the *NO coupling chemistry. In a further control experiment Cu(+) ion is added to ((6)L)Fe(NO)(2) without acid present, [((6)L)Fe(NO)...Cu(II)(NO(2)(-))](+) is obtained, with the amount of N(2)O((g)) released fitting with copper(I) ion promoted disproportionation chemistry, 3*NO + ligand-Cu(I) --> N(2)O + ligand-Cu(II)(NO(2)(-)). The chemical system described represents a (stoichiometric) functional model for heme/Cu protein nitric oxide reductase activity.

| S-EPMC2662328 | biostudies-literature

Photomediated reductive coupling of nitroarenes with aldehydes for amide synthesis.

Project description:In view of the widespread significance of amide functional groups in organic synthesis and pharmaceutical studies, an efficient and practical synthetic protocol that avoids the use of stoichiometric activating reagents or metallic reductants is highly desirable. A straight-forward pathway to access amides from abundant chemical feedstock would offer a strategic advantage in the synthesis of complex amides. We herein disclose a direct reductive amidation reaction using readily available aldehydes and nitroarenes enabled by photo-mediated hydrogen atom transfer catalysis. It avoids the use of metallic reductants and production of toxic chemical waste. While aldehydes represent a classic class of electrophilic synthons, the corresponding nucleophilic acyl radicals could be directly accessed by photo hydrogen atom transfer catalysis, enabling polarity inversion. Our method provides an orthogonal strategy to conventional amide couplings, tolerating nucleophilic substituents such as free alcohols and sensitive functional groups to amines such as carbonyl or formyl groups. The synthetic utilization of this reductive amidation is demonstrated by the late-stage modification of complex biologically active molecules and direct access of drug molecules leflunomide and lidocaine.

| S-EPMC9384791 | 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