Browse
Submit Data
Databases
API
Help

Dataset Information

52 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Asymmetric Michael Addition Organocatalyzed by ?,?-Dipeptides under Solvent-Free Reaction Conditions.

ABSTRACT: The application of six novel ?,?-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and N-arylmaleimides or nitroolefins is described. With N-arylmaleimides as substrates, the best results were achieved with dipeptide 2 as a catalyst in the presence of aq. NaOH. Whereas dipeptides 4 and 6 in conjunction with 4-dimethylaminopyridine (DMAP) and thiourea as a hydrogen bond donor proved to be highly efficient organocatalytic systems in the enantioselective reaction between isobutyraldehyde and various nitroolefins.

SUBMITTER: Avila-Ortiz CG

PROVIDER: S-EPMC6152315 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Asymmetric Michael Addition Organocatalyzed by α,β-Dipeptides under Solvent-Free Reaction Conditions.

Avila-Ortiz C Gabriela CG Díaz-Corona Lenin L Jiménez-González Erika E Juaristi Eusebio E

Molecules (Basel, Switzerland) 20170810 8

The application of six novel α,β-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and N-arylmaleimides or nitroolefins is described. With N-arylmaleimides as substrates, the best results were achieved with dipeptide 2 as a catalyst in the presence of aq. NaOH. Whereas dipeptides 4 and 6 in conjunction with 4-dimethylaminopyridine (DMAP) and thiourea as a hydrogen bond donor proved to be highly efficie ...[more]

PMID: 28796165

Similar Datasets

Organocatalyzed asymmetric Michael reaction of ?-aryl-?-ketophosphonates and nitroalkenes.

Project description:The first enantioselective Michael reaction of ?-aryl-?-ketophosphonates and nitroalkenes has been brealized by using a new bifunctional Takemoto-type thiourea catalyst. The primary Michael adducts obtained were converted in situ to the corresponding amides through the aminolysis. High yields, excellent diastereoselectivities (>95:5 dr), and good enantioselectivities (up to 81% ee) have been achieved for the corresponding ? ,?-disubstituted ?-nitroamides. This reaction againdemon strated that ?-ketophosphonates are interesting pronucleophiles that can be used as amide surrogates in organocatalyzed reactions.

| S-EPMC3810965 | biostudies-literature

Efficacy of Selenourea Organocatalysts in Asymmetric Michael Reactions under Standard and Solvent-Free Conditions.

Project description:By varying the steric and electronic surroundings of the hydrogen-bonding motif, the novel chiral Cinchona-alkaloid based selenoureas were developed. Acting as bifunctional catalysts, they were applied in the Michael reactions of dithiomalonate and nitrostyrene providing chiral adducts with up to 96% ee. The asymmetric Michael--hemiacetalization reaction of benzylidene pyruvate and dimedone, performed with the assistance of 5 mol% of selenoureas, furnished the product with up to 93% ee and excellent yields. The effectiveness of the new hydrogen-bond donors was also proved in solvent-free reactions under ball mill conditions, supporting the sustainability of the devised catalytic protocol.

| S-EPMC8658871 | biostudies-literature

Asymmetric 1,4-Michael Addition Reaction of Azadienes with α-Thiocyanoindanones Catalyzed by Bifunctional Chiral Squaramide.

Project description:In this paper, the organocatalytic asymmetric 1,4-Michael addition reaction of azadienes and α-thiocyanoindanones was investigated. A series of chiral benzofuran compounds containing thiocyano group and quaternary carbon center were synthesized in moderate yields with good enantioselectivities (up to 90:10 er) and high diastereoselectivities (up to >95:5 dr). This is the first case of 1,4-Michael addition reaction using α-thiocyanoindanones to obtain a series of chiral thiocyano compounds and further broaden the scope of application of azadiene substrates. In addition, a possible reaction mechanism is also described in the article.

| S-EPMC8456331 | biostudies-literature

A general organocatalyzed Michael-Michael cascade reaction generates functionalized cyclohexenes.

Project description:Although ?-dicarbonyl compounds are regularly employed as Michael donors, intermediates arising from the Michael addition of unsaturated ?-ketoesters to ?,?-unsaturated aldehydes are susceptible to multiple subsequent reaction pathways. We designed cyclic unsaturated ?-ketoester substrates that enabled the development of the first diphenyl prolinol silyl ether catalyzed Michael-Michael cascade reaction initiated by a ?-dicarbonyl Michael donor to form cyclohexene products. The reaction conditions we developed for this Michael-Michael cascade reaction were also amenable to a variety of linear unsaturated ?-ketoester substrates, including some of the same linear unsaturated ?-ketoester substrates that were previously ineffective in Michael-Michael cascade reactions. These studies thus revealed that a change in simple reaction conditions, such as solvent and additives, enables the same substrate to undergo different cascade reactions, thereby accessing different molecular scaffolds. These studies also culminated in the development of a general organocatalyzed Michael-Michael cascade reaction that generates highly functionalized cyclohexenes with up to four stereocenters, in up to 97% yield, 32:1 dr, and 99% ee, in a single step from a variety of unsaturated ?-ketoesters.

| S-EPMC3198797 | biostudies-literature

Enantioselective synthesis of beta-(3-hydroxypyrazol-1-yl) ketones using an organocatalyzed Michael addition reaction.

Project description:Beta-(3-hydroxypyrazol-1-yl) ketones have been prepared in high yields and excellent enantioselectivities (94-98% ee) via a Michael addition reaction between 2-pyrazolin-5-ones and aliphatic acyclic alpha,beta-unsaturated ketones using 9-epi-9-amino-9-deoxyquinine as the catalyst. These results account for the first example of an aza-Michael addition of the ambident 2-pyrazolin-5-one anion to a Michael acceptor.

| S-EPMC2752151 | biostudies-literature

A new organocatalyzed Michael-Michael cascade reaction generates highly substituted fused carbocycles.

Project description:While beta-ketoesters are useful Michael donors, they were previously ineffective in Michael-Michael cascade reactions using alpha,beta-unsaturated aldehydes in conjunction with diphenylprolinol silyl ether organocatalysts. However, through rational modification of substrates and manipulation of the catalytic cycle, we developed an efficient Michael-Michael cascade reaction using beta-ketoesters of type 9. In this transformation, highly substituted fused carbocycles are generated in a single step in up to 87% yield and 99% ee.

| S-EPMC2802209 | biostudies-literature

Enantioselective Organocatalyzed Michael Addition of Isobutyraldehyde to Maleimides in Aqueous Media.

Project description:Thiourea was introduced into (R,R)-1,2-diphenylethylenediamine as an organocatalyst to promote the reaction between isobutyraldehydes and maleimides. Enantioselective Michael addition reaction was carried out as an eco-friendly method using water as the solvent. As a result of the reaction between isobutyraldehyde and maleimide, ≥97% yield and 99% enantioselectivity were obtained at a low catalyst loading of 0.01 mol%. The solvent effect can be explained by theoretical calculations that indicate the participation of a transition state, in which the CF3 substituent of the catalyst is a hydrogen bond activated by the surrounding water molecules. This discovery enabled the use of low catalyst loading in the organic reactions of chiral substances for pharmaceutical applications. Furthermore, a solvent effect for Michael reaction of the organocatalysts was proposed, and the organic reaction mechanisms were determined through quantum calculations.

| S-EPMC9101813 | biostudies-literature

Cinchona Squaramide-Based Chiral Polymers as Highly Efficient Catalysts in Asymmetric Michael Addition Reaction.

Project description:We have synthesized novel chiral polymers containing a cinchona-based squaramide in the main chain. We designed a novel cinchona squaramide dimer that contains two cinchona squaramide units connected by diamines. The olefinic double bonds in the cinchona squaramide dimer were used for Mizoroki-Heck (MH) polymerization with aromatic diiodides. The MH polymerization of the cinchona squaramide dimer and aromatic diiodide proceeded well to give the corresponding chiral polymers in good yields. The catalytic activity of the chiral polymers was investigated for asymmetric Michael addition reactions. The effect of the squaramide structure of the polymeric catalyst on the catalytic performance is discussed in detail. We have surveyed the influence of the chiral polymer structure on the catalytic activity and enantioselectivity of the asymmetric reaction. The asymmetric Michael addition of β-ketoesters to nitroolefins was successfully catalyzed by polymeric cinchona squaramide organocatalysts to obtain the corresponding Michael adducts in good yields with excellent enantio- and diastereoselectivities. The polymeric catalysts were insoluble in commonly used organic solvents and easily recovered from the reaction mixture and reused several times without the loss of catalytic activity.

| S-EPMC6641636 | biostudies-literature

Catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to nitroalkenes by a grinding method.

Project description:An environmentally benign, fast and convenient protocol has been developed for the Michael addition of 1,3-dicarbonyl compounds to β-nitroalkenes in good to excellent yields by a grinding method under catalyst- and solvent-free conditions.

| S-EPMC3343280 | biostudies-literature

Asymmetric Organocatalytic Sulfa-Michael Addition to Enone Diesters.

Project description:An asymmetric sulfa-Michael addition of alkyl thiols to enone diesters is reported. The reaction is catalyzed by a bifunctional triaryliminophosphorane-thiourea organocatalyst and provides a range of α-sulfaketones in high yields and enantioselectivities. Leveraging the gem-diester functional handle via a subsequent diastereotopic group discrimination generates functionalized lactones with three contiguous stereocenters.

| S-EPMC5856655 | 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