Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Manganese complex-catalyzed oxidation and oxidative kinetic resolution of secondary alcohols by hydrogen peroxide.

ABSTRACT: The highly efficient catalytic oxidation and oxidative kinetic resolution (OKR) of secondary alcohols has been achieved using a synthetic manganese catalyst with low loading and hydrogen peroxide as an environmentally benign oxidant in the presence of a small amount of sulfuric acid as an additive. The product yields were high (up to 93%) for alcohol oxidation and the enantioselectivity was excellent (>90% ee) for the OKR of secondary alcohols. Mechanistic studies revealed that alcohol oxidation occurs via hydrogen atom (H-atom) abstraction from an α-CH bond of the alcohol substrate and a two-electron process by an electrophilic Mn-oxo species. Density functional theory calculations revealed the difference in reaction energy barriers for H-atom abstraction from the α-CH bonds of R- and S-enantiomers by a chiral high-valent manganese-oxo complex, supporting the experimental result from the OKR of secondary alcohols.

SUBMITTER: Miao C

PROVIDER: S-EPMC5676093 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Highly Efficient Kinetic Resolution of Aryl-Alkenyl Alcohols by Ru-Catalyzed Hydrogen Transfer.

Project description:No matter through asymmetric reduction of ketones or kinetic resolution of secondary alcohols, enantioselective synthesis of the corresponding secondary alcohols is challenging when the two groups attached to the prochiral or chiral centers are spatially or electronically similar. For examples, dialkyl (sp3 vs. sp3), diaryl (sp2 vs. sp2), and aryl-alkenyl (sp2 vs. sp2) alcohols are difficult to produce with high enantioselectivities. By exploiting our recently developed Ru-catalysts of minimal stereogenicity, we reported herein a highly efficient kinetic resolution of aryl-alkenyl alcohols through hydrogen transfer. This method enabled such versatile chiral building blocks for organic synthesis as allylic alcohols, to be readily accessed with excellent enantiomeric excesses at practically useful conversions.

| S-EPMC8705739 | biostudies-literature

Origin of enantioselectivity in CF3-PIP-catalyzed kinetic resolution of secondary benzylic alcohols.

Project description:Computational studies provide support for the involvement of intermolecular pi-interactions in the chiral recognition of secondary benzylic alcohols by the enantioselective acyl transfer catalyst CF3-PIP.

| S-EPMC2663394 | biostudies-literature

The palladium-catalyzed aerobic kinetic resolution of secondary alcohols: reaction development, scope, and applications.

Project description:The first palladium-catalyzed enantioselective oxidation of secondary alcohols has been developed, utilizing the readily available diamine (-)-sparteine as a chiral ligand and molecular oxygen as the stoichiometric oxidant. Mechanistic insights regarding the role of the base and hydrogen-bond donors have resulted in several improvements to the original system. Namely, addition of cesium carbonate and tert-butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. The use of chloroform as solvent allows the use of ambient air as the terminal oxidant at 23 degrees C, resulting in enhanced catalyst selectivity. These improved reaction conditions have permitted the successful kinetic resolution of benzylic, allylic, and cyclopropyl secondary alcohols to high enantiomeric excess with good-to-excellent selectivity factors. This catalyst system has also been applied to the desymmetrization of meso-diols, providing high yields of enantioenriched hydroxyketones.

| S-EPMC2862982 | biostudies-literature

Highly Enantioselective Oxidation of Nonactivated Aliphatic C-H Bonds with Hydrogen Peroxide Catalyzed by Manganese Complexes.

Project description:Monosubstituted cycloalkanes undergo regio- and enantioselective aliphatic C-H oxidation with H2O2 catalyzed by biologically inspired manganese catalysts. The reaction furnishes the corresponding ketones resulting from oxidation at C3 and C4 methylenic sites (K3 and K4, respectively) leading to a chiral desymmetrization that proceeds with remarkable enantioselectivity (64% ee) but modest regioselectivity at C3 (K3/K4 ≈ 2) for tert-butylcyclohexane, and with up to 96% ee and exquisite regioselectity toward C3 (up to K3/K4 > 99) when N-cyclohexylalkanamides are employed as substrates. Efficient H2O2 activation, high yield, and highly enantioselective C-H oxidation rely on the synergistic cooperation of a sterically bulky manganese catalyst and an oxidatively robust alkanoic acid. This represents the first example of nonenzymatic highly enantioselective oxidation of nonactivated methylenic sites. Furthermore, the principles of catalyst design disclosed in this work constitute a unique platform for further development of stereoselective C-H oxidation reactions.

| S-EPMC5364455 | biostudies-literature

The Size-Accelerated Kinetic Resolution of Secondary Alcohols.

Project description:The factors responsible for the kinetic resolution of alcohols by chiral pyridine derivatives have been elucidated by measurements of relative rates for a set of substrates with systematically growing aromatic side chains using accurate competitive linear regression analysis. Increasing the side chain size from phenyl to pyrenyl results in a rate acceleration of more than 40 for the major enantiomer. Based on this observation a new catalyst with increased steric bulk has been designed that gives enantioselectivity values of up to s=250. Extensive conformational analysis of the relevant transition states indicates that alcohol attack to the more crowded side of the acyl-catalyst intermediate is favoured due to stabilizing CH-π-stacking interactions. Experimental and theoretical results imply that enantioselectivity enhancements result from accelerating the transformation of the major enantiomer through attractive non-covalent interactions (NCIs) rather than retarding the transformation of the minor isomer through repulsive steric forces.

| S-EPMC7821155 | biostudies-literature

Manganese(I)-Catalyzed Cross-Coupling of Ketones and Secondary Alcohols with Primary Alcohols.

Project description:Catalytic cross-coupling of ketones and secondary alcohols with primary alcohols is reported. An abundant manganese-based pincer catalyst catalyzes the reactions. Low loading of catalyst (2 mol %) and catalytic use of a mild base (5-10 mol %) are sufficient for efficient cross-coupling. Various aryl and heteroaryl ketones are catalytically cross-coupled with primary alcohols to provide the selective α-alkylated products. Challenging α-ethylation of ketones is also attained using ethanol as an alkylating reagent. Further, direct use of secondary alcohols in the reaction results in in situ oxidation to provide the ketone intermediates, which undergo selective α-alkylation. The reaction proceeds via the borrowing hydrogen pathway. The catalyst oxidizes the primary alcohols to aldehydes, which undergo subsequent aldol condensation with ketones, promoted by catalytic amount of Cs2CO3, to provide the α,β-unsaturated ketone intermediates. The hydrogen liberated from oxidation of alcohols is used for hydrogenation of α,β-unsaturated ketone intermediates. Notably either water or water and dihydrogen are the only byproducts in these environmentally benign catalytic processes. Mechanistic studies allowed inferring all of the intermediates involved. Dearomatization-aromatization metal-ligand cooperation in the catalyst facilitates the facile O-H bond activation of both primary and secondary alcohols, and the resultant manganese alkoxide complexes produce corresponding carbonyl compounds, perhaps via β-hydride elimination. The manganese(I) hydride intermediate plays dual role as it hydrogenates α,β-unsaturated ketones and liberates molecular hydrogen to regenerate the catalytically active dearomatized intermediate. Metal-ligand cooperation allows all of the manganese intermediates to exist in same oxidation state (+1) and plays an important role in these catalytic cross-coupling reactions.

| S-EPMC6648503 | biostudies-literature

Kinetic resolution of secondary alcohols using amidine-based catalysts.

Project description:Kinetic resolution of racemic alcohols has been traditionally achieved via enzymatic enantioselective esterification and ester hydrolysis. However, there has long been considerable interest in devising nonenzymatic alternative methods for this transformation. Amidine-based catalysts (ABCs), a new class of enantioselective acyl transfer catalysts developed in our group, have demonstrated, inter alia, high efficacy in the kinetic resolution of benzylic, allylic, and propargylic secondary alcohols and 2-substituted cycloalkanols, and thus provide a viable alternative to enzymes.

| S-EPMC3291098 | biostudies-literature

Tungsten-catalyzed asymmetric epoxidation of allylic and homoallylic alcohols with hydrogen peroxide.

Project description:A simple, efficient, and environmentally friendly asymmetric epoxidation of primary, secondary, tertiary allylic, and homoallylic alcohols has been accomplished. This process was promoted by a tungsten-bishydroxamic acid complex at room temperature with the use of aqueous 30% H2O2 as oxidant, yielding the products in 84-98% ee.

| S-EPMC3985688 | biostudies-literature

Ruthenium-Catalyzed Amination of Secondary Alcohols using Borrowing Hydrogen Methodology.

Project description:A new ruthenium complex catalyzes the amination of primary and secondary alcohols and the regioselective mono- and sequential diamination of diols via the borrowing hydrogen pathway. Several variations on new intra- and intermolecular cyclizations of aminoalcohols, diols and diamines lead to heterocyclic ring systems.

| S-EPMC5604847 | biostudies-literature

Structural features and reactivity of (sparteine)PdCl2: a model for selectivity in the oxidative kinetic resolution of secondary alcohols.

Project description:The chiral ligand (-)-sparteine and PdCl(2) catalyze the enantioselective oxidation of secondary alcohols to ketones and thus effect a kinetic resolution. The structural features of sparteine that led to the selectivity observed in the reaction were not clear. Substitution experiments with pyridine derivatives and structural studies of the complexes generated were carried out on (sparteine)PdCl(2) and indicated that the C(1) symmetry of (-)-sparteine is essential to the location of substitution at the metal center. Palladium alkoxides were synthesized from secondary alcohols that are relevant steric models for the kinetic resolution. The solid-state structures of the alkoxides also confirmed the results from the pyridine derivative substitution studies. A model for enantioinduction was developed with C(1) symmetry and Cl(-) as key features. Further studies of the diastereomers of (-)-sparteine, (-)-alpha-iso- and (+)-beta-isosparteine, in the kinetic resolution showed that these C(2)-symmetric counterparts are inferior ligands in this stereoablative reaction [Mohr, J. T., Ebner, D. C., and Stoltz, B. M. Org. Biomol. Chem. 2007, 5, 3571-3576].

| S-EPMC2649720 | 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