Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Catalytic asymmetric reactions for organic synthesis: the combined C-H activation/Cope rearrangement.

ABSTRACT: The development of new catalytic asymmetric reactions can lead to exciting new strategies for organic synthesis. This article describes the synthetic utility of the combined C-H activation/Cope rearrangement, achieved by dirhodium tetraprolinate-catalyzed reaction of vinyldiazoacetates with compounds containing allylic C-H bonds. The transformation is highly diastereoselective and enantioselective. The product distribution, however, is highly substrate dependent, the major side products being either direct C-H activation or cyclopropanation.

SUBMITTER: Davies HM

PROVIDER: S-EPMC397407 | biostudies-literature | 2004 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Catalytic asymmetric reactions for organic synthesis: the combined C-H activation/Cope rearrangement.

Davies Huw M L HM Jin Qihui Q

Proceedings of the National Academy of Sciences of the United States of America 20040315 15

The development of new catalytic asymmetric reactions can lead to exciting new strategies for organic synthesis. This article describes the synthetic utility of the combined C-H activation/Cope rearrangement, achieved by dirhodium tetraprolinate-catalyzed reaction of vinyldiazoacetates with compounds containing allylic C-H bonds. The transformation is highly diastereoselective and enantioselective. The product distribution, however, is highly substrate dependent, the major side products being ei ...[more]

PMID: 15024094

Similar Datasets

Asymmetric Synthesis of β-Amino Amides by Catalytic Enantioconvergent 2-Aza-Cope Rearrangement.

Project description:Dynamic kinetic resolutions of α-stereogenic-β-formyl amides in asymmetric 2-aza-Cope rearrangements are described. Chiral phosphoric acids catalyze this rare example of a non-hydrogenative DKR of a β-oxo acid derivative. The [3,3]-rearrangement occurs with high diastereo- and enantiocontrol, forming β-imino amides that can be deprotected to the primary β-amino amide or reduced to the corresponding diamine.

| S-EPMC4661081 | biostudies-literature

Catalytic asymmetric synthesis of quaternary trifluoromethyl α- to ε-amino acid derivatives <i>via</i> umpolung allylation/2-aza-Cope rearrangement.

Project description:In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement of tertiary α-trifluoromethyl α-amino acid derivatives for the preparation of a variety of quaternary α-trifluoromethyl α-amino acids in high yields with excellent enantioselectivities. The umpolung reactivity empowered by the activation of the key isatin-ketoimine moiety obviates the intractable enantioselectivity control in Pd-catalyzed asymmetric linear α-allylation. In combination with quasi parallel kinetic resolution or kinetic resolution, the generality of this method is further demonstrated by the first preparation of enantioenriched quaternary trifluoromethyl β-, γ-, δ- and ε-amino acid derivatives.

| S-EPMC8162408 | biostudies-literature

Catalytic asymmetric ?-Iminol rearrangement: new chiral platforms.

Project description:A series of 19 different asymmetric catalysts were screened in an effort to identify the first chiral catalyst for the rearrangement of ?-hydroxy imines to ?-amino ketones involving a 1,2-carbon shift. Although aluminate complexes of VAPOL, VANOL, and 7,7'-(t)Bu2VANOL were quite effective catalysts giving up to 88% ee, the ne plus ultra catalyst for this reaction was found to be a zirconium complex of VANOL which gives 97 to >99% ee for the majority of the substrates examined. An X-ray diffraction study of the catalyst reveals that the zirconium exists as a homoleptic complex with three VANOL ligands and two protonated N-methyl imidazoles.

| S-EPMC4195388 | biostudies-literature

Catalytic Asymmetric Synthesis of Chiral ?-Amino Ketones via Umpolung Reactions of Imines.

Project description:The first direct catalytic asymmetric synthesis of ?-amino ketones was realized by the development of a highly diastereoselective and enantioselective C-C bond-forming umpolung reaction of imines and enones under the catalysis of a new cinchona alkaloid-derived phase-transfer catalyst. In a loading ranging from 0.02 to 2.5 mol %, the catalyst activates a broad range of trifluoromethyl imines and aldimines as nucleophiles to engage in chemo-, regio-, diastereo- and enantioselective C-C bond-forming reactions with acyclic and cyclic enones, thereby converting these readily available prochiral starting materials into highly enantiomerically enriched chiral ?-amino ketones in synthetically useful yields. Enabled by this unprecedented umpolung reaction of imines, conceptually new and concise routes were developed for the asymmetric synthesis of nitrogen-heterocycles such as pyrrolidines and indolizidines.

| S-EPMC5654742 | biostudies-literature

Catalytic asymmetric umpolung reactions of imines.

Project description:The carbon-nitrogen double bonds in imines are fundamentally important functional groups in organic chemistry. This is largely due to the fact that imines act as electrophiles towards carbon nucleophiles in reactions that form carbon-carbon bonds, thereby serving as one of the most widely used precursors for the formation of amines in both synthetic and biosynthetic settings. If the carbon atom of the imine could be rendered electron-rich, the imine could react as a nucleophile instead of as an electrophile. Such a reversal in the electronic characteristics of the imine functionality would facilitate the development of new chemical transformations that convert imines into amines via carbon-carbon bond-forming reactions with carbon electrophiles, thereby creating new opportunities for the efficient synthesis of amines. The development of asymmetric umpolung reactions of imines (in which the imines act as nucleophiles) remains uncharted territory, in spite of the far-reaching impact such reactions would have in organic synthesis. Here we report the discovery and development of new chiral phase-transfer catalysts that promote the highly efficient asymmetric umpolung reactions of imines with the carbon electrophile enals. These catalysts mediate the deprotonation of imines and direct the 2-azaallyl anions thus formed to react with enals in a highly chemoselective, regioselective, diastereoselective and enantioselective fashion. The reaction tolerates a broad range of imines and enals, and can be carried out in high yield with as little as 0.01 mole per cent catalyst with a moisture- and air-tolerant operational protocol. These umpolung reactions provide a conceptually new and practical approach to chiral amino compounds.

| S-EPMC4513368 | biostudies-literature

Catalytic Asymmetric Synthesis of meta Benzene Isosteres

Project description:Aromatic rings are common elements in pharmaceutically active compounds; however, their ready oxidation can present a liability with respect to a drug's metabolic stability. Replacing these aromatic rings in pharmaceutical compounds with non-aromatic isosteric motifs can enhance properties such as potency, metabolic stability, solubility, and lipophilicity. Since the binding pockets of most pharmaceutical targets are chiral, the stereochemical configuration of the isosteric replacements are expected to have an impact on the affinity of derived ligands for target receptors. A significant impediment to this approach is the lack of simple, and scalable catalytic enantioselective syntheses of candidate isosteres from readily available precursors. In this work, we present a heretofore unknown palladium-catalyzed reaction that converts hydrocarbon-derived precursors to chiral boron-containing nortricyclanes and we show that that shape of these nortricyclanes makes them plausible isosteres for meta disubstituted aromatic rings. With chiral catalysts, the Pd-catalyzed reaction can be accomplished in an enantioselective fashion and subsequent transformation of the boron group provides access to a broad array of structures. We also show that incorporation of nortricyclanes into pharmaceutical motifs can result in improved biophysical properties along with stereochemistry-dependent activity. We anticipate that these features, coupled with the simple, inexpensive synthesis of the functionalized nortricyclane scaffold will render this platform a useful foundation for assembly of new biologically active agents.

2024-09-11 | PXD051400 | Pride

Catalytic, asymmetric, interrupted Feist-Benary reactions of ?-tosyloxyacetophenones.

Project description:A new variant of the Interrupted Feist-Bénary (IFB) reaction uses ?-tosyloxyacetophenones as electrophiles and proceeds in good yields and excellent enantioselectivities.

| S-EPMC3226731 | biostudies-literature

Catalytic asymmetric synthesis of geminal-dicarboxylates.

Project description:Stereogenic acetals, spiroacetals and ketals are well-studied stereochemical features that bear two heteroatoms at a common carbon atom. These stereocenters are normally found in cyclic structures while linear (or acyclic) analogues bearing two heteroatoms are rare. Chiral geminal-dicarboxylates are illustrative, there is no current way to access this class of compounds while controlling the stereochemistry at the carbon center bound to two oxygen atoms. Here we report a rhodium-catalysed asymmetric carboxylation of ester-containing allylic bromides to form stereogenic carbon centers bearing two different carboxylates with high yields and enantioselectivities. The products, which are surprisingly stable to a variety of acidic and basic conditions, can be manipulated with no loss of enantiomeric purity as demonstrated by ring closing metathesis reactions to form chiral lactones, which have been extensively used as building blocks in asymmetric synthesis.

| S-EPMC6063137 | biostudies-literature

Catalytic asymmetric formal synthesis of beraprost.

Project description:The first catalytic asymmetric synthesis of the key intermediate for beraprost has been achieved through an enantioselective intramolecular oxa-Michael reaction of an ?,?-unsaturated amide mediated by a newly developed benzothiadiazine catalyst. The Weinreb amide moiety and bromo substituent of the Michael adduct were utilized for the C-C bond formations to construct the scaffold. All four contiguous stereocenters of the tricyclic core were controlled via Rh-catalyzed stereoselective C-H insertion and the subsequent reduction from the convex face.

| S-EPMC4685892 | biostudies-literature

Synthesis of icariin from kaempferol through regioselective methylation and para-Claisen-Cope rearrangement.

Project description:The hemisynthesis of the naturally occurring bioactive flavonoid glycoside icariin (1) has been accomplished in eleven steps with 7% overall yield from kaempferol. The 4'-OH methylation of kaempferol, the 8-prenylation of 3-O-methoxymethyl-4'-O-methyl-5-O-prenyl-7-O-benzylkaempferol (8) via para-Claisen-Cope rearrangement catalyzed by Eu(fod)3 in the presence of NaHCO3, and the glycosylation of icaritin (3) are the key steps.

| S-EPMC4578360 | 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