Asymmetric Catalysis

article

An Improved Protocol for the Preparation of New 1, 2, 3 Triazolium Based Ionic Liquids and their Application as solvent for Aldol reaction

Vivek Srivastava

Asymmetric Catalysis > 2013 > 1 > 1

Microwave heating was used to synthesise different types of 1, 2, 3 triazolium based ionic liquids (5a-j) with good yield in reduced time. These ionic liquids were further screened as reaction medium for Aldol reaction using two different most promising organocatalysts; proline and proline tetrazole. In both cases, Aldol products were obtained in good yield and selectivity with each ionic liquid....

article

Exciting time in Organocatalysis

R. Rios, T. Gasperi

Asymmetric Catalysis > 2013 > 1 > 1

article

Comparison of Supported and Unsupported Proline Derivatives in Asymmetric Aminocatalytic Transformations

Vivek Srivastava

Asymmetric Catalysis > 2013 > 1 > 1

Organocatalysis, where organic molecules like α-amino acids, α-hydroxy acids, nucleic acids, carbohydrates are employed to catalyze organic transformations such as the aldol, Mannich and Michael reactions is a rapidly expanding field of organic synthesis. Operational simplicity, ready availability of the catalysts, selectivity, efficiency and low cost make them an attractive alternative to metal-mediated...

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Asymmetric Pd-catalyzed allylic substitution using a large sugar-based monophosphite ligand library. Scope and limitations.

Sabina Alegre, Yvette Matta, Montserrat Diéguez, Oscar Pàmies

Asymmetric Catalysis > 2013 > 1 > 1

We have applied a modular sugar-based phosphite ligand library for the Pd-catalyzed allylic substitution reactions of several substrates. These ligands are derived from D-(+)-glucose, D-(+)-galactose and D-(+)- fructose, which lead to a wide range of sugar backbones, and contain several substituents at the C-3 carbon of the furanoside backbone and several substituents/ configurations in the biaryl...

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Trienamines: Their Key Role in Extended Organocatalysis for Diels-Alder Reactions

Silvia Reboredo, Alejandro Parra, José Alemán

Asymmetric Catalysis > 2013 > 1 > 1

Activation via trienamine intermediates is a synthetically useful protocol for performing asymmetric Diels-Alder reactions controlled by a remote chiral catalyst (a secondary or primary amine). Key features underpinning this concept are the conformation towards the trienamine formation and also the use of highly electrophilic dienophiles. This cycloaddition reaction allows the application of asymmetric...

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One-pot synthesis of (R)-convolutamydine A involving in situ chiral organocatalyst formation

Shengwei Wei, Bernhard Schmid, Fliur Z. Macaev, Serghei N. Curlat, more

Asymmetric Catalysis > 2015 > 2 > 1

The application of a convenient one-pot synthetic strategy, utilizing an in situ formed organocatalyst, to the enantioselective synthesis of anti-leukaemia agent (R)-convolutamydine A has been demonstrated. <fig fig-type="graphical" position="float" orientation="portrait"> <graphic xlink.href="graphic/asorg-2014-0002-graphabs.jpg" position="float"...

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New feats of alkene and alkyne asymmetric hydroamination catalyzed by copper and rhodium hydrides

Alessandro Dondoni

Asymmetric Catalysis > 2015 > 2 > 1

Hydroamination of unsaturated carbon-carbon bonds is a useful C-N bond forming reaction as it leads to products (amines, imines, enamines) of high synthetic value. While the hydroamination of terminal alkenes and alkynes under metal catalysis has been widely developed, the corresponding reactions with internal substrates remain a challenge. Two recent studies by Buchwald and by Dong which focus on...

article

Chiral Counterion Strategy in Cu-Catalyzed Asymmetric Allylic Oxidation of Linear Alkenes

Celia A. Incerti-Pradillos, Daniel Hudson, Andrei V. Malkov

Asymmetric Catalysis > 2015 > 2 > 1

Application of a chiral counter-ion strategy in the Kharasch-Sosnovsky reaction is reported. Copper(I) phosphates obtained from axially chiral, BINOL-derived phosphoric acids were investigated as catalysts in the enantioselective allylic oxidation of acyclic alkenes. Good yields and high regioselectivity towards branched allylic ester have been achieved. The chiral phosphates investigated exhibited...

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Use of (R)-Mandelic Acid as Chiral Co-Catalyst in the Michael Addition Reaction Organocatalyzed by (1S,4S)-2-Tosyl-2,5-diazabicyclo[2.2.1]heptane under Solvent-Free Conditions

C. Gabriela Ávila-Ortiz, Manuel López-Ortiz, Alberto Vega-Peñaloza, Ignacio Regla, more

Asymmetric Catalysis > 2015 > 2 > 1

This article describes a study on the Michael addition reaction of cyclohexanone to nitroolefins catalyzed by the chiral secondary amine (1S,4S)-2-tosyl- 2,5-diazabicyclo[2.2.1]heptane. Reactions were carried out under solvent-free conditions to make them more environmentally friendly. Initially, the observed diastereoand enantioselectivities were moderate to good, but were significantly improved...

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Synthesis of novel chiral bithiophenebased phosphine oxides as Lewis bases in organocatalytic stereoselective reactions

Sergio Rossi, Maurizio Benaglia, Roberto Cirilli, Tiziana Benincori

Asymmetric Catalysis > 2015 > 2 > 1

Novel enantiomerically pure tetramethylbithiophene diphosphine oxides (tetraMe-BITIOPO) featuring differently substituted aromatic rings at the phosphorous atoms were synthesized, fully characterized and isolated in enantiomerically pure form. The new Lewis bases were tested as organocatalysts in two different reactions involving trichlorosilyl compounds. The introduction of electron donating substituents...

article

Solvent-controlled diastereoselectivity in tryptophan-catalyzed Mannich reactions

Guillem Valero, Carlos M. León, Albert Moyano

Asymmetric Catalysis > 2015 > 2 > 1

Solvent effects in the L-tryptophan-catalyzed Mannich reaction between hydroxyacetone and glyoxylate imines have been examined. The use of a DMSO/1-butanol (4:1 v/v) mixture as solvent at rt provided the expected Mannich adducts in good yields, high anti-diastereoselectivity (up to 10.3:1 anti/syn ratio) and excellent enantioselectivities (up to >99.9% ee for the anti isomer).

article

Organocatalytic Enantioselective [3+2] Cycloaddition of Azomethine Ylides and Acrolein

Iratxe Ugarriza, Uxue Uria, Efraím Reyes, Luisa Carrillo, more

Asymmetric Catalysis > 2015 > 2 > 1

The [3+2]-cycloaddition reaction between acrolein and in situ generated acyclic azomethine ylides promoted by a chiral secondary amine to generate C-3 unsubstituted pyrrolidines has been studied in detail. Optimum conditions involve the use of the cheap and readily available l-Proline as catalyst to afford the pyrrolidine cycloadduct with complete diastereomeric control and up to 80% enantiomeric...

INFONA - science communication portal

Asymmetric Catalysis

An Improved Protocol for the Preparation of New 1, 2, 3 Triazolium Based Ionic Liquids and their Application as solvent for Aldol reaction

Exciting time in Organocatalysis

Comparison of Supported and Unsupported Proline Derivatives in Asymmetric Aminocatalytic Transformations

Asymmetric Pd-catalyzed allylic substitution using a large sugar-based monophosphite ligand library. Scope and limitations.

Trienamines: Their Key Role in Extended Organocatalysis for Diels-Alder Reactions

One-pot synthesis of (R)-convolutamydine A involving in situ chiral organocatalyst formation

New feats of alkene and alkyne asymmetric hydroamination catalyzed by copper and rhodium hydrides

Chiral Counterion Strategy in Cu-Catalyzed Asymmetric Allylic Oxidation of Linear Alkenes

Use of (R)-Mandelic Acid as Chiral Co-Catalyst in the Michael Addition Reaction Organocatalyzed by (1S,4S)-2-Tosyl-2,5-diazabicyclo[2.2.1]heptane under Solvent-Free Conditions

Synthesis of novel chiral bithiophenebased phosphine oxides as Lewis bases in organocatalytic stereoselective reactions

Solvent-controlled diastereoselectivity in tryptophan-catalyzed Mannich reactions

Organocatalytic Enantioselective [3+2] Cycloaddition of Azomethine Ylides and Acrolein

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