Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A General Regioselective Synthesis of Alcohols by Cobalt-Catalyzed Hydrogenation of Epoxides.

ABSTRACT: A straightforward methodology for the synthesis of anti-Markovnikov-type alcohols is presented. By using a specific cobalt triphos complex in the presence of Zn(OTf)2 as an additive, the hydrogenation of epoxides proceeds with high yields and selectivities. The described protocol shows a broad substrate scope, including multi-substituted internal and terminal epoxides, as well as a good functional-group tolerance. Various natural-product derivatives, including steroids, terpenoids, and sesquiterpenoids, gave access to the corresponding alcohols in moderate-to-excellent yields.

SUBMITTER: Liu W

PROVIDER: S-EPMC7383699 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

A General Regioselective Synthesis of Alcohols by Cobalt-Catalyzed Hydrogenation of Epoxides.

Liu Weiping W Leischner Thomas T Li Wu W Junge Kathrin K Beller Matthias M

Angewandte Chemie (International ed. in English) 20200511 28

A straightforward methodology for the synthesis of anti-Markovnikov-type alcohols is presented. By using a specific cobalt triphos complex in the presence of Zn(OTf)<sub>2</sub> as an additive, the hydrogenation of epoxides proceeds with high yields and selectivities. The described protocol shows a broad substrate scope, including multi-substituted internal and terminal epoxides, as well as a good functional-group tolerance. Various natural-product derivatives, including steroids, terpenoids, an ...[more]

PMID: 32196878

Similar Datasets

Mechanism of Cobalt-Catalyzed CO Hydrogenation: 2. Fischer-Tropsch Synthesis.

Project description:Fischer-Tropsch (FT) synthesis is one of the most complex catalyzed chemical reactions in which the chain-growth mechanism that leads to formation of long-chain hydrocarbons is not well understood yet. The present work provides deeper insight into the relation between the kinetics of the FT reaction on a silica-supported cobalt catalyst and the composition of the surface adsorbed layer. Cofeeding experiments of 12C3H6 with 13CO/H2 evidence that CH x surface intermediates are involved in chain growth and that chain growth is highly reversible. We present a model-based approach of steady-state isotopic transient kinetic analysis measurements at FT conditions involving hydrocarbon products containing up to five carbon atoms. Our data show that the rates of chain growth and chain decoupling are much higher than the rates of monomer formation and chain termination. An important corollary of the microkinetic model is that the fraction of free sites, which is mainly determined by CO pressure, has opposing effects on CO consumption rate and chain-growth probability. Lower CO pressure and more free sites leads to increased CO consumption rate but decreased chain-growth probability because of an increasing ratio of chain decoupling over chain growth. The preferred FT condition involves high CO pressure in which chain-growth probability is increased at the expense of the CO consumption rate.

| S-EPMC5716444 | biostudies-literature

Access to stereodefined (Z)-allylsilanes and (Z)-allylic alcohols via cobalt-catalyzed regioselective hydrosilylation of allenes.

Project description:Hydrosilylation of allenes is the addition of a hydrogen atom and a silyl group to a carbon-carbon double bond of an allene molecule and represents a straightforward and atom-economical approach to prepare synthetically versatile allylsilanes and vinylsilanes. However, this reaction generally produces six possible isomeric organosilanes, and the biggest challenge in developing this reaction is to control both regioselectivity and stereoselectivity. The majorities of the developed allene hydrosilylation reactions show high selectivity towards the production of vinylsilanes or branched allylsilanes. By employing a cobalt catalyst generated from readily available and bench-stable cobalt precursor and phosphine-based ligands, here we show that this reaction proceeds under mild conditions in a regioselective and stereoselective manner, and affords synthetically challenging, but valuable linear cis-allylsilanes with excellent stereoselectivity (generally cis to trans ratios: >98:2). This cobalt-catalyzed (Z)-selective allene hydrosilylation provides a general approach to access molecules containing stereodefined (Z)-alkene units.

| S-EPMC5741631 | biostudies-literature

Regioselective Hydrohydroxyalkylation of Styrene with Primary Alcohols or Aldehydes via Ruthenium-Catalyzed C-C Bond Forming Transfer Hydrogenation.

Project description:Transfer hydrogenative coupling of styrene with primary alcohols using the precatalyst HClRu(CO)(PCy3 )2 modified by AgOTf or HBF4 delivers branched or linear adducts from benzylic or aliphatic alcohols, respectively. Related 2-propanol mediated reductive couplings also are described.

| S-EPMC5189692 | biostudies-literature

Expedient and divergent synthesis of unnatural peptides through cobalt-catalyzed diastereoselective umpolung hydrogenation.

Project description:The development of a reliable method for asymmetric synthesis of unnatural peptides is highly desirable and particularly challenging. In this study, we present a versatile and efficient approach that uses cobalt-catalyzed diastereoselective umpolung hydrogenation to access noncanonical aryl alanine peptides. This protocol demonstrates good tolerance toward various functional groups, amino acid sequences, and peptide lengths. Moreover, the versatility of this reaction is illustrated by its successful application in the late-stage functionalization and formal synthesis of various representative chiral natural products and pharmaceutical scaffolds. This strategy eliminates the need for synthesizing chiral noncanonical aryl alanines before peptide formation, and the hydrogenation reaction does not result in racemization or epimerization. The underlying mechanism was extensively explored through deuterium labeling, control experiments, HRMS identification, and UV-Vis spectroscopy, which supported a reasonable CoI/CoIII catalytic cycle. Notably, acetic acid and methanol serve as safe and cost-effective hydrogen sources, while indium powder acts as the terminal electron source.

| S-EPMC10732522 | biostudies-literature

Cobalt-catalyzed alkene hydrogenation by reductive turnover.

Project description:Earth abundant metal catalysts hold advantages in cost, environmental burden and chemoselectivity over precious metal catalysts. Differences in reactivity for a given metal center result from ligand field strength, which can promote reaction through either open- or closed-shell carbon intermediates. Herein we report a simple protocol for cobalt-catalyzed alkene reduction. Instead of using an oxidative turnover mechanism that requires stoichiometric hydride, we find a reductive turnover mechanism that requires stoichiometric proton. The reaction mechanism appears to involve coordination and hydrocobaltation of terminal alkenes.

| S-EPMC10573012 | biostudies-literature

Photo-Initiated Cobalt-Catalyzed Radical Olefin Hydrogenation.

Project description:Outer-sphere radical hydrogenation of olefins proceeds via stepwise hydrogen atom transfer (HAT) from transition metal hydride species to the substrate. Typical catalysts exhibit M-H bonds that are either too weak to efficiently activate H2 or too strong to reduce unactivated olefins. This contribution evaluates an alternative approach, that starts from a square-planar cobalt(II) hydride complex. Photoactivation results in Co-H bond homolysis. The three-coordinate cobalt(I) photoproduct binds H2 to give a dihydrogen complex, which is a strong hydrogen atom donor, enabling the stepwise hydrogenation of both styrenes and unactivated aliphatic olefins with H2 via HAT.

| S-EPMC9292329 | biostudies-literature

Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides.

Project description:The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.

| S-EPMC8935656 | biostudies-literature

Iron-Catalyzed Transfer Hydrogenation of Allylic Alcohols with Isopropanol.

Project description:Herein, we report an iron-catalyzed transfer hydrogenation of allylic alcohols. The operationally simple protocol employs a well-defined bench stable (cyclopentadienone)iron(0) carbonyl complex as a precatalyst in combination with K2CO3 (4 mol %) and isopropanol as the hydrogen donor. A diverse range of allylic alcohols undergo transfer hydrogenation to form the corresponding alcohols in good yields (33 examples, ≤83% isolated yield). The scope and limitations of the method have been investigated, and experiments that shed light on the reaction mechanism have been conducted.

| S-EPMC11459429 | biostudies-literature

Mechanism of Cobalt-Catalyzed CO Hydrogenation: 1. Methanation.

Project description:The mechanism of CO hydrogenation to CH4 at 260 °C on a cobalt catalyst is investigated using steady-state isotopic transient kinetic analysis (SSITKA) and backward and forward chemical transient kinetic analysis (CTKA). The dependence of CH x residence time is determined by 12CO/H2 → 13CO/H2 SSITKA as a function of the CO and H2 partial pressure and shows that the CH4 formation rate is mainly controlled by CH x hydrogenation rather than CO dissociation. Backward CO/H2 → H2 CTKA emphasizes the importance of H coverage on the slow CH x hydrogenation step. The H coverage strongly depends on the CO coverage, which is directly related to CO partial pressure. Combining SSITKA and backward CTKA allows determining that the amount of additional CH4 obtained during CTKA is nearly equal to the amount of CO adsorbed to the cobalt surface. Thus, under the given conditions overall barrier for CO hydrogenation to CH4 under methanation condition is lower than the CO adsorption energy. Forward CTKA measurements reveal that O hydrogenation to H2O is also a relatively slow step compared to CO dissociation. The combined transient kinetic data are used to fit an explicit microkinetic model for the methanation reaction. The mechanism involving direct CO dissociation represents the data better than a mechanism in which H-assisted CO dissociation is assumed. Microkinetics simulations based on the fitted parameters confirms that under methanation conditions the overall CO consumption rate is mainly controlled by C hydrogenation and to a smaller degree by O hydrogenation and CO dissociation. These simulations are also used to explore the influence of CO and H2 partial pressure on possible rate-controlling steps.

| S-EPMC5716442 | biostudies-literature

Copolymerization of epoxides with cyclic anhydrides catalyzed by dinuclear cobalt complexes.

Project description:The alternating copolymerization of epoxides with cyclic anhydrides (CAs) is a highly diverse synthetic method for polyesters as the polymers' architectures and properties can be easily controlled depending on the combination of two monomers. Thus, a variety of catalyst designs has been reported to prepare the desired copolymers efficiently. We herein report dinuclear cobalt-salen complexes with a benzene ring as a linker and their activities in copolymerization reactions. The dinuclear cobalt complexes showed a higher catalytic activity for the copolymerization of propylene oxide with phthalic anhydride than the corresponding mononuclear cobalt-salen complex and achieved one of the highest turnover frequencies ever reported. A variety of epoxides and CAs were also found to be copolymerized successfully by the dinuclear cobalt complex with a high catalytic activity.

| S-EPMC6244378 | 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