Browse
Submit Data
Databases
API
Help

Dataset Information

9 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Synthesis of the Core Framework of the Cornexistins by Intramolecular Nozaki-Hiyama-Kishi Coupling.

ABSTRACT: A new and direct approach to the construction of the core framework of the herbicidal natural products cornexistin and hydroxycornexistin has been developed. Formation of the nine-membered carbocycle found in the natural products has been accomplished by an intramolecular Nozaki-Hiyama-Kishi reaction between a vinylic iodide and an aldehyde. Good yields of carbocyclic products were obtained from the reaction, but diastereomeric mixtures of allylic alcohols were produced. The cyclisation reaction was successful irrespective of the relative configuration of the stereogenic centres in the cyclisation precursor.

SUBMITTER: Aimon A

PROVIDER: S-EPMC6680490 | biostudies-other | 2019 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Publications

Synthesis of the Core Framework of the Cornexistins by Intramolecular Nozaki-Hiyama-Kishi Coupling.

Aimon Anthony A Farrugia Louis J LJ Clark J Stephen JS

Molecules (Basel, Switzerland) 20190722 14

A new and direct approach to the construction of the core framework of the herbicidal natural products cornexistin and hydroxycornexistin has been developed. Formation of the nine-membered carbocycle found in the natural products has been accomplished by an intramolecular Nozaki-Hiyama-Kishi reaction between a vinylic iodide and an aldehyde. Good yields of carbocyclic products were obtained from the reaction, but diastereomeric mixtures of allylic alcohols were produced. The cyclisation reaction ...[more]

PMID: 31336669

Similar Datasets

Intramolecular anodic olefin coupling reactions and the synthesis of cyclic amines.

Project description:Anodic olefin coupling reactions using a tosylamine trapping group have been studied. The cyclizations are favored by the use of a less-polar radical cation and more basic reaction conditions. The most significant factor for obtaining good yields of cyclic product is the use of the more basic reaction conditions. However, a number of factors including the nature of both the solvent and the electrolyte used can influence the yield of the cyclizations. The cyclizations allow for the rapid synthesis of both substituted proline and pipecolic acid type derivatives.

| S-EPMC3950632 | biostudies-literature

Microwave-assisted synthesis of macrocycles via intramolecular and/or bimolecular Ullmann coupling.

Project description:Microwave-assisted synthesis of macrocyclic diaryl ethers via intramolecular and/or bimolecular Ullmann coupling is described. Using the optimized conditions, a panel of macrocycles, with different substitution patterns, ring sizes, and linkers, has been successfully synthesized using microwave irradiation. To the best of our knowledge, this work represents the first examples of the microwave-assisted synthesis of macrocyclic diaryl ethers via intramolecular and/or bimolecular Ullmann coupling.

| S-EPMC3462461 | biostudies-literature

Synthesis of alkaloid (-)-205B via stereoselective reductive cross-coupling and intramolecular [3+2] cycloaddition.

Project description:An asymmetric synthesis of alkaloid (-)-205B, a tricyclic member of the architecturally diverse family of natural products isolated from the skin of neotropical poison frogs, is described that proceeds through two recently developed stereoselective synthetic methods: (1) Ti-mediated allylic alcohol-imine reductive cross-coupling and (2) intramolecular [3+2] cycloaddition of a glyoxylate-based homoallylic nitrone. The utility of this latter cycloaddition process for the assembly of the stereochemically dense piperidine core of 205B is noteworthy, as this method enables direct [3+2] cycloaddition of an intermediate homoallylic (E)-nitrone via a pathway that is stereochemically unscathed by competitive [3,3]-sigmatropic rearrangement processes. Overall, the synthesis is asymmetric, concise, and highly stereoselective-features which point to the potential future utility of these chemical methods in natural product synthesis and medicinal chemistry.

| S-EPMC3470905 | biostudies-literature

Microwave-assisted synthesis of 3-nitroindoles from N-aryl enamines via intramolecular arene-alkene coupling.

Project description:A variety of N-aryl ?-nitroenamines were effectively transformed into 3-nitroindoles in good yields and with complete regioselectivity via a rapid microwave (?W) assisted intramolecular arene-alkene coupling reaction. This report further demonstrates the versatility of this method by constructing 3-carboalkoxy- and 3-cyanoindoles. Optimization data, substrate scope, and applications are discussed.

| S-EPMC3549302 | biostudies-literature

Synthesis of the cytotrienin A core via metal catalyzed C-C coupling.

Project description:A synthetic approach to the C17-benzene ansamycins via metal catalyzed C-C coupling is described. Key bond formations include direct iridium catalyzed carbonyl crotylation from the alcohol oxidation level followed by chelation-controlled Sakurai-Seyferth dienylation to form the stereotriad, which is attached to the arene via Suzuki cross-coupling. The diene-containing carboxylic acid is prepared using rhodium catalyzed acetylene-aldehyde reductive C-C coupling mediated by gaseous hydrogen. Finally, ring-closing metathesis delivers the cytotrienin core.

| S-EPMC3075014 | biostudies-literature

Intrinsic Coupling of Lagging Strand Synthesis to Chromatin Assembly

Project description:We show that ligation-competent Okazaki fragments in Saccharomyces cerevisiae are sized according to the chromatin repeat. Using deep sequencing, we demonstrate that ligation junctions preferentially occur around nucleosome midpoints rather than in internucleosomal linker regions. Disrupting chromatin assembly or lagging strand polymerase processivity impacts both the size and the distribution of Okazaki fragments, suggesting a role for nascent chromatin, assembled immediately after the passage of the replication fork, in the termination of lagging strand synthesis. Our studies represent the first high-resolution analysis of eukaryotic Okazaki fragments in vivo, and establish a mechanistic link between the fundamental processes of DNA replication and chromatin assembly. 4 samples: replicate samples of wild-type and pol32 knockout

2012-02-21 | E-GEOD-33786 | biostudies-arrayexpress

Single-step synthesis and interface tuning of core-shell metal-organic framework nanoparticles.

Project description:Control over the spatial distribution of components in metal-organic frameworks has potential to unlock improved performance and new behaviour in separations, sensing and catalysis. We report an unprecedented single-step synthesis of multi-component metal-organic framework (MOF) nanoparticles based on the canonical ZIF-8 (Zn) system and its Cd analogue, which form with a core-shell structure whose internal interface can be systematically tuned. We use scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and a new composition gradient model to fit high-resolution X-ray diffraction data to show how core-shell composition and interface characteristics are intricately controlled by synthesis temperature and reaction composition. Particle formation is investigated by in situ X-ray diffraction, which reveals that the spatial distribution of components evolves with time and is determined by the interplay of phase stability, crystallisation kinetics and diffusion. This work opens up new possibilities for the control and characterisation of functionality, component distribution and interfaces in MOF-based materials.

| S-EPMC8179513 | biostudies-literature

Probing intramolecular vibronic coupling through vibronic-state imaging.

Project description:Vibronic coupling is a central issue in molecular spectroscopy. Here we investigate vibronic coupling within a single pentacene molecule in real space by imaging the spatial distribution of single-molecule electroluminescence via highly localized excitation of tunneling electrons in a controlled plasmonic junction. The observed two-spot orientation for certain vibronic-state imaging is found to be evidently different from the purely electronic 0-0 transition, rotated by 90°, which reflects the change in the transition dipole orientation from along the molecular short axis to the long axis. Such a change reveals the occurrence of strong vibronic coupling associated with a large Herzberg-Teller contribution, going beyond the conventional Franck-Condon picture. The emergence of large vibration-induced transition charges oscillating along the long axis is found to originate from the strong dynamic perturbation of the anti-symmetric vibration on those carbon atoms with large transition density populations during electronic transitions.

| S-EPMC7904785 | biostudies-literature

Intramolecular Coupling of Terminal Alkynes by Atom Manipulation.

Project description:Glaser-like coupling of terminal alkynes by thermal activation is extensively used in on-surface chemistry. Here we demonstrate an intramolecular version of this reaction performed by atom manipulation. We used voltage pulses from the tip to trigger a Glaser-like coupling between terminal alkyne carbons within a custom-synthesized precursor molecule adsorbed on bilayer NaCl on Cu(111). Different conformations of the precursor molecule and the product were characterized by molecular structure elucidation with atomic force microscopy and orbital density mapping with scanning tunneling microscopy, accompanied by density functional theory calculations. We revealed partially dehydrogenated intermediates, providing insight into the reaction pathway.

| S-EPMC7756451 | biostudies-literature

Development of a general, sequential, ring-closing metathesis/intramolecular cross-coupling reaction for the synthesis of polyunsaturated macrolactones.

Project description:A general strategy for the construction of macrocyclic lactones containing conjugated Z,Z-1,3-diene subunits is described. The centerpiece of the strategy is a sequential ring-closing metathesis (RCM) that forms an unsaturated siloxane ring, followed by an intramolecular cross-coupling reaction with a pendant alkenyl iodide. A highly modular assembly of the various precursors allowed the preparation of unsaturated macrolactones containing 11-, 12-, 13-, and 14-membered rings. Although the RCM process proceeded uneventfully, the intramolecular cross-coupling required extensive optimization of palladium source, solvent, fluoride source, and particularly fluoride hydration level. Under the optimal conditions (including syringe pump high dilution), the macrolactones were produced in 53-78% yield as single stereoisomers. A benzo-fused 12-membered-ring macrolactone containing an E,Z-1,3-diene unit was also prepared by the same general strategy. The E-2-styryl iodide was prepared by a novel Heck reaction of an aryl nonaflate with vinyltrimethylsilane followed by iododesilylation with ICl.

| S-EPMC2923678 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

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