Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Rhodium-catalyzed asymmetric hydrogenation of β-cyanocinnamic esters with the assistance of a single hydrogen bond in a precise position.

ABSTRACT: With the assistance of hydrogen bonds, the first asymmetric hydrogenation of β-cyanocinnamic esters is developed, affording chiral β-cyano esters with excellent enantioselectivities (up to 99% ee). This novel methodology provides an efficient and concise synthetic route to chiral GABA-derivatives such as (S)-Pregabalin, (R)-Phenibut, (R)-Baclofen. Interestingly, in this system, the catalyst with a single H-bond donor performs better than that with double H-bond donors, which is a novel discovery in the metalorganocatalysis area.

SUBMITTER: Li X

PROVIDER: S-EPMC5890790 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Rhodium-catalyzed asymmetric hydrogenation of β-cyanocinnamic esters with the assistance of a single hydrogen bond in a precise position.

Li Xiuxiu X You Cai C Yang Yusheng Y Yang Yuhong Y Li Pan P Gu Guoxian G Chung Lung Wa LW Lv Hui H Zhang Xumu X

Chemical science 20180104 7

With the assistance of hydrogen bonds, the first asymmetric hydrogenation of β-cyanocinnamic esters is developed, affording chiral β-cyano esters with excellent enantioselectivities (up to 99% ee). This novel methodology provides an efficient and concise synthetic route to chiral GABA-derivatives such as (S)-Pregabalin, (R)-Phenibut, (R)-Baclofen. Interestingly, in this system, the catalyst with a single H-bond donor performs better than that with double H-bond donors, which ...[more]

PMID: 29675238

Similar Datasets

Selective hydrogenation via precise hydrogen bond interactions on catalytic scaffolds.

Project description:The active site environment in enzymes has been known to affect catalyst performance through weak interactions with a substrate, but precise synthetic control of enzyme inspired heterogeneous catalysts remains challenging. Here, we synthesize hyper-crosslinked porous polymer (HCPs) with solely -OH or -CH3 groups on the polymer scaffold to tune the environment of active sites. Reaction rate measurements, spectroscopic techniques, along with DFT calculations show that HCP-OH catalysts enhance the hydrogenation rate of H-acceptor substrates containing carbonyl groups whereas hydrophobic HCP- CH3 ones promote non-H bond substrate activation. The functional groups go beyond enhancing substrate adsorption to partially activate the C = O bond and tune the catalytic sites. They also expose selectivity control in the hydrogenation of multifunctional substrates through preferential substrate functional group adsorption. The proposed synthetic strategy opens a new class of porous polymers for selective catalysis.

| S-EPMC9879947 | biostudies-literature

Rhodium-catalyzed asymmetric hydrogenation of unprotected NH imines assisted by a thiourea.

Project description:Asymmetric hydrogenation of unprotected NH imines catalyzed by rhodium/bis(phosphine)-thiourea provided chiral amines with up to 97% yield and 95% ee. (1)H NMR studies, coupled with control experiments, implied that catalytic chloride-bound intermediates were involved in the mechanism through a dual hydrogen-bonding interaction. Deuteration experiments proved that the hydrogenation proceeded through a pathway consistent with an imine.

| S-EPMC5989712 | biostudies-literature

Rational Optimization of Supramolecular Catalysts for the Rhodium-Catalyzed Asymmetric Hydrogenation Reaction.

Project description:Rational design of catalysts for asymmetric transformations is a longstanding challenge in the field of catalysis. In the current contribution we report a catalyst in which a hydrogen bond between the substrate and the catalyst plays a crucial role in determining the selectivity and the rate of the catalytic hydrogenation reaction, as is evident from a combination of experiments and DFT calculations. Detailed insight allowed in silico mutation of the catalyst such that only this hydrogen bond interaction is stronger, predicting that the new catalyst is faster. Indeed, we experimentally confirmed that optimization of the catalyst can be realized by increasing the hydrogen bond strength of this interaction by going from a urea to phosphine oxide H-bond acceptor on the ligand.

| S-EPMC6123616 | biostudies-literature

Remarkably Facile Borane-Promoted, Rhodium-Catalyzed Asymmetric Hydrogenation of Tri- and Tetrasubstituted Alkenes.

Project description:Oxime-directed catalytic asymmetric hydroboration is diverted to catalytic asymmetric hydrogenation (CAH) upon the addition of a proton source, such as MeOH, or by running the reaction under a hydrogen atmosphere. A borane (e.g., pinacolborane) is required to promote CAH. Tri- and tetrasubstituted alkenes, including the challenging all-alkyl tetrasubstituted alkenes, undergo CAH with enantiomer ratios (er) as high as 99:1. The mild reaction conditions, i.e., ambient temperature, moderate reaction times, and the need for only a slight excess of H2, contrast those used in most state-of-the-art catalysts for related substrates.

| S-EPMC5408738 | biostudies-literature

Hydrogen-mediated reductive coupling of conjugated alkynes with ethyl (N-Sulfinyl)iminoacetates: synthesis of unnatural alpha-amino acids via rhodium-catalyzed C-C bond forming hydrogenation.

Project description:Rhodium-catalyzed hydrogenation of 1,3-enynes 1a-8a and 1,3-diynes 9a-13a at ambient temperature and pressure in the presence of ethyl (N-tert-butanesulfinyl)iminoacetate and ethyl (N-2,4,6-triisopropylbenzenesulfinyl)iminoacetates, respectively, results in reductive coupling to afford unsaturated alpha-amino acid esters 1b-13b in good to excellent yields with exceptional levels of regio- and stereocontrol. Further hydrogenation of the diene containing alpha-amino acid esters 1b-8b using Wilkinson's catalyst at ambient temperature and pressure results in regioselective reduction to afford the beta,gamma-unsaturated alpha-amino acid esters 1c-8c in good to excellent yields. Exhaustive hydrogenation of the unsaturated side chains of the Boc- and Fmoc-protected derivatives of enyne and diyne coupling products 14b-16b occurs in excellent yield using Crabtree's catalyst at ambient temperature and pressure providing the alpha-amino acid esters 14d-16d, which possess saturated side chains. Finally, cross-metathesis of the Boc-protected reductive coupling product 14b with cis-1,4-diacetoxy-2-butene proceeds readily to afford the allylic acetate 14e. Isotopic labeling studies that involve reductive coupling of enyne 1a and diyne 9a under an atmosphere of elemental deuterium corroborate a catalytic mechanism in which oxidative coupling of the alkyne and imine residues is followed by hydrogenolytic cleavage of the resulting metallacycle. A stereochemical model accounting for the observed sense of asymmetric induction is provided. These studies represent the first use of imines as electrophilic partners in hydrogen-mediated reductive carbon-carbon bond formation.

| S-EPMC2625294 | biostudies-literature

Branch-selective reductive coupling of 2-vinyl pyridines and imines via rhodium catalyzed C-C bond forming hydrogenation.

Project description:Hydrogenation of 2-vinyl azines 1a-1e in the presence of N-arylsulfonyl imines 2a-2l at ambient temperature and pressure employing cationic rhodium catalysts ligated by tri-2-furylphosphine results in regioselective reductive coupling to furnish branched products of imine addition 3a-3v, which embody modest to high levels of syn-diastereoselectivity. Catalytic coupling of 6-bromo-2-vinylpyridine 1a to imine 2l under an atmosphere of elemental deuterium provides deuterio-3l, with deuterium exclusively at the former beta-position of the vinyl moiety. These data are consistent with a catalytic mechanism involving oxidative coupling of the vinyl azine and imine partners to furnish a cationic aza-rhodacyclopentane, which upon deuteriolytic cleavage releases the adduct and regenerates cationic rhodium(I) to close the catalytic cycle. These studies represent the first metal catalyzed reductive C-C couplings of vinyl azines.

| S-EPMC2844715 | biostudies-literature

Rhodium-Catalyzed Asymmetric Arylation of Cyclobutenone Ketals.

Project description:Complex cyclobutanes are important motifs in both bioactive molecules and natural products, yet their enantioselective preparation has not been widely explored. In this work, we describe rhodium-catalyzed enantioselective additions of aryl and vinyl boronic acids to cyclobutenone ketals. This transformation involves enantioselective carbometalation to give cyclobutyl-rhodium intermediates, followed by β-oxygen elimination to afford enantioenriched enol ethers. Overall, this addition serves as a surrogate for Rh-catalyzed 1,4-additions to cyclobutenone.

| S-EPMC10946970 | biostudies-literature

Rhodium-Catalyzed Asymmetric Functionalization of Quinoxalinium Salts.

Project description:We report a rhodium-catalyzed asymmetric addition of aryl and alkenyl boronic acids to quinoxalinium salts that generates dihydroquinoxalines with high enantioselectivity. Functionalization of the reaction products, dihydroquinoxaline, allows the preparation of tetrahydroquinoxalines with various substitution patterns.

| S-EPMC11032262 | biostudies-literature

Rhodium-Catalyzed Asymmetric Hydroamination of Allyl Amines.

Project description:A Rh-catalyzed enantioselective hydroamination of allylamines using a chiral BIPHEP-type ligand is reported. Enantioenriched 1,2-diamines are formed in good yields and with excellent enantioselectivities. A diverse array of nucleophiles and amine directing groups are demonstrated, including deprotectable motifs. Finally, the methodology was demonstrated toward the rapid synthesis of 2-methyl-moclobemide.

| S-EPMC6693864 | biostudies-literature

Ni-catalyzed asymmetric hydrogenation of N-aryl imino esters for the efficient synthesis of chiral α-aryl glycines.

Project description:Chiral α-aryl glycines play a key role in the preparation of some bioactive products, however, their catalytic asymmetric synthesis is far from being satisfactory. Herein, we report an efficient nickel-catalyzed asymmetric hydrogenation of N-aryl imino esters, affording chiral α-aryl glycines in high yields and enantioselectivities (up to 98% ee). The hydrogenation can be conducted on a gram scale with a substrate/catalyst ratio of up to 2000. The obtained chiral N-p-methoxyphenyl α-aryl glycine derivatives are not only directly useful chiral secondary amino acid esters but can also be easily deprotected by treatment with cerium ammonium nitrate for further transformations to several widely used molecules including drug intermediates and chiral ligands. Formation of a chiral Ni-H species in hydrogenation is detected by 1H NMR. Computational results indicate that the stereo selection is determined during the approach of the substrate to the catalyst.

| S-EPMC7683563 | 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