Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Synthesis of Anti-beta-substituted gamma,delta-unsaturated amino acids via Eschenmoser-Claisen rearrangement.

ABSTRACT: Anti-beta-substituted gamma,delta-unsaturated amino acids have been synthesized via a novel design of the Eschenmoser-Claisen rearrangement. The rearrangement gives good isolated yields and excellent diastereoselectivity due to (Z)-N,O-ketene acetal formation and the pseudochairlike conformations of the reaction intermediates. Upon reductive hydrolysis, important novel amino acids and amino alcohols were synthesized for the first time via this methodology.

SUBMITTER: Qu H

PROVIDER: S-EPMC2366803 | biostudies-literature | 2006 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Synthesis of Anti-beta-substituted gamma,delta-unsaturated amino acids via Eschenmoser-Claisen rearrangement.

Qu Hongchang H Gu Xuyuan X Min Byoung J BJ Liu Zhihua Z Hruby Victor J VJ

Organic letters 20060901 19

Anti-beta-substituted gamma,delta-unsaturated amino acids have been synthesized via a novel design of the Eschenmoser-Claisen rearrangement. The rearrangement gives good isolated yields and excellent diastereoselectivity due to (Z)-N,O-ketene acetal formation and the pseudochairlike conformations of the reaction intermediates. Upon reductive hydrolysis, important novel amino acids and amino alcohols were synthesized for the first time via this methodology. ...[more]

PMID: 16956190

Similar Datasets

Enantioselective synthesis of anti-beta-substituted gamma,delta-unsaturated amino acids: a highly selective asymmetric thio-Claisen rearrangement.

Project description:A novel synthesis of optically active anti-beta-substituted gamma,delta-unsaturated amino acids via a thio-Claisen rearrangement has been achieved. A 2,5-diphenylpyrrolidine was used as a C2-symmetric chiral auxiliary to control the stereochemistry, giving good yields and excellent diastereoselectivities and enantioselectivities.

| S-EPMC2654228 | biostudies-literature

Synthesis of gamma,delta-unsaturated glycolic acids via sequenced brook and Ireland--claisen rearrangements.

Project description:Organozinc, -magnesium, and -lithium nucleophiles initiate a Brook/Ireland-Claisen rearrangement sequence of allylic silyl glyoxylates resulting in the formation of gamma,delta-unsaturated alpha-silyloxy acids.

| S-EPMC2830285 | biostudies-literature

Radical Functionalization of Unsaturated Amino Acids: Synthesis of Side-Chain-Fluorinated, Azido-Substituted, and Hydroxylated Amino Acids.

Project description:A range of enantiomerically pure protected side-chain-fluorinated amino acids has been prepared (13 examples) by treatment of protected amino acids containing unsaturated side chains with a combination of Fe(III)/NaBH4 and Selectfluor. The modification of the conditions by replacement of Selectfluor with NaN3 allowed the preparation of side-chain azido-substituted amino acids (five examples), which upon catalytic hydrogenation gave the corresponding amines, isolated as lactams (four examples). Radical hydration of the unsaturated side chains leading to side-chain-hydroxylated protected amino acids has also been demonstrated.

| S-EPMC6648964 | biostudies-literature

Pd-catalyzed γ-arylation of γ,δ-unsaturated O-carbamates via an unusual haptotropic rearrangement.

Project description:An unusual γ-selectivity was observed in the arylation of γ,δ-unsaturated O-carbamates involving directed lithiation, transmetallation to zinc and Negishi coupling, when a specific combination of aryl electrophile and phosphine ligand is employed. Mechanistic studies indicate that an unusual, stereospecific haptotropic rearrangement of the palladium-diene intermediate is involved.

| S-EPMC6385668 | biostudies-other

Global Diastereoconvergence in the Ireland-Claisen Rearrangement of Isomeric Enolates: Synthesis of Tetrasubstituted α-Amino Acids.

Project description:A dual experimental/theoretical investigation of the Ireland-Claisen rearrangement of tetrasubstituted α-phthalimido ester enolates to afford α-tetrasubstituted, β-trisubstituted α-amino acids (generally >20:1 dr) is described. For trans allylic olefins, the Z- and E-enol ethers proceed through chair and boat transition states, respectively. For cis allylic olefins, the trend is reversed. As a result, the diastereochemical outcome of the reaction is preserved regardless of the geometry of the enolate or the accompanying allylic olefin. We term this unique convergence of all possible olefin isomers global diastereoconvergence. This reaction manifold circumvents limitations in present-day technologies for the stereoselective enolization of α,α-disubstituted allyl esters. Density functional theory paired with state-of-the-art local coupled-cluster theory (DLPNO-CCSD(T)) was employed for the accurate determination of quantum mechanical energies.

| S-EPMC8552564 | biostudies-literature

Copper-Catalyzed Decarboxylative Functionalization of Conjugated <i>β,γ</i>-Unsaturated Carboxylic Acids.

Project description:Copper-catalyzed decarboxylative coupling reactions of conjugated β,γ-unsaturated carboxylic acids have been achieved for allylic amination, alkylation, sulfonylation, and phosphinoylation. This approach was effective for a broad scope of amino, alkyl, sulfonyl, and phosphinoyl radical precursors as well as various conjugated β,γ-unsaturated carboxylic acids. These reactions also feature high regioselectivity, good functional group tolerance, and simple operation procedure. Mechanistic studies show that the reaction proceeds via copper-catalyzed electrophilic addition onto an olefin followed by decarboxylation, with radical intermediates involved. These insights present a modular and powerful strategy to access versatilely functionalized allyl-containing skeletons from readily available and stable carboxylic acids.

| S-EPMC8346209 | biostudies-literature

Photoredox-enabled 1,2-dialkylation of α-substituted acrylates <i>via</i> Ireland-Claisen rearrangement.

Project description:Herein, we report the 1,2-dialkylation of simple feedstock acrylates for the synthesis of valuable tertiary carboxylic acids by merging Giese-type radical addition with an Ireland-Claisen rearrangement. Key to success is the utilization of the reductive radical-polar crossover concept under photocatalytic reaction conditions to force the [3,3]-sigmatropic rearrangement after alkyl radical addition to allyl acrylates. Using readily available alkyl boronic acids as radical progenitors, this redox-neutral, transition-metal-free protocol allows the mild formation of two C(sp3)-C(sp3) bonds, thus providing rapid access to complex tertiary carboxylic acids in a single step. Moreover, this strategy enables the efficient synthesis of highly attractive α,α-dialkylated γ-amino butyric acids (GABAs) when α-silyl amines are used as radical precursors - a structural motif that was still inaccessible in related transformations. Depending on the nature of the radical precursors and their inherent oxidation potentials, either a photoredox-induced radical chain or a solely photoredox mechanism is proposed to be operative.

| S-EPMC8179405 | biostudies-literature

Preparation of bicyclic 1,2,4-trioxanes from gamma,delta-unsaturated ketones.

Project description:Treatment of gamma,delta-unsaturated ketones with hydrogen peroxide and acid provides a rapid entry into the medicinally important 1,2,4-trioxane structure. Alkene substitution that stabilizes carbocationic intermediates proved to be important for the success of this transformation.

| S-EPMC2657341 | biostudies-literature

Transforming Olefins into γ,δ-Unsaturated Nitriles through Copper Catalysis.

Project description:We have developed a strategy to transform olefins into homoallylic nitriles through a mechanism that combines copper catalysis with alkyl nitrile radicals. The radicals are easily generated from alkyl nitriles in the presence of the mild oxidant di-tert-butyl peroxide. This cross-dehydrogenative coupling between simple olefins and alkylnitriles bears advantages over the conventional use of halides and toxic cyanide reagents. With this method, we showcase the facile synthesis of a flavoring agent, a natural product, and a polymer precursor from simple olefins.

| S-EPMC6824592 | biostudies-literature

Chemoselective γ-Oxidation of β,γ-Unsaturated Amides with TEMPO.

Project description:A chemoselective and robust protocol for the γ-oxidation of β,γ-unsaturated amides is reported. In this method, electrophilic amide activation, in a rare application to unsaturated amides, enables a regioselective reaction with TEMPO resulting in the title products. Radical cyclisation reactions and oxidation of the synthesised products highlight the synthetic utility of the products obtained.

| S-EPMC8456850 | 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