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13 results on '"Morwenna S. M. Pearson-Long"'

1. Asymmetric Titanium-Catalyzed Cyclopropanation of Nitriles with Grignard Reagents

Author

Julien Caillé, Paul Setzer, Fabien Boeda, Morwenna S. M. Pearson-Long, and Philippe Bertus

Subjects
cyclopropanes, enantioselectivity, grignard reagents, nitriles­, spiro compounds, titanium, Chemistry, QD1-999
Abstract

Abstract The titanium-catalyzed asymmetric cyclopropanation of cyanoesters­ with Grignard reagents was investigated for the first time. Particularly, the study of the efficiency of Taddol-based titanium complexes­ has shown that the prior preparation of Taddol titanium complexes was not required and a large panel of ligands was evaluated by using this approach. The spirocyclopropanelactams were obtained with good diastereoselectivity and with moderate enantioselectivities from the main diastereoisomer (up to 32%).

Published
2018
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3. A Short Access to Symmetrically α,α-Disubstituted α-Amino Acids from Acyl Cyanohydrins

Author

Florian Rouzier, Fabien Boeda, Julien Caillé, Philippe Bertus, Morwenna S. M. Pearson-Long, Houcine Ammar, Fatma Boukattaya, Institut des Molécules et Matériaux du Mans (IMMM), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Faculté des Sciences de Sfax, and Université de Sfax - University of Sfax

Subjects
chemistry.chemical_classification, amino acids, Grignard reagents, [CHIM.ORGA]Chemical Sciences/Organic chemistry, 010405 organic chemistry, Chemistry, Stereochemistry, Organic Chemistry, Nucleophilic acyl substitution, solvent effects, 010402 general chemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Amino acid, Acylation, Reagent, Moiety, cyanohydrins, nitriles, Solvent effects, Chemoselectivity
Abstract

International audience; A straightforward synthesis of symmetrically α,α-disubstituted α-amino acids is presented. The key step of this process relies on the efficient double addition of Grignard reagents to acyl cyanohydrins to provide N-acyl amino alcohols selectively in good yields. The chemoselectivity of the reaction was modulated by the nature of the acyl moiety. Eleven amino acids were prepared, including the particularly simple divinylglycine, which is not easily accessible by using conventional methods.

Published
2016

4. Asymmetric Titanium-Catalyzed Cyclopropanation of Nitriles with Grignard Reagents

Author

Morwenna S. M. Pearson-Long, Fabien Boeda, Paul Setzer, Julien Caillé, Philippe Bertus, Institut des Molécules et Matériaux du Mans (IMMM), and Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
cyclopropanes, Grignard reagents, 010405 organic chemistry, Chemistry, Cyclopropanation, spiro compounds, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Materials Science (miscellaneous), Organic Chemistry, Diastereomer, chemistry.chemical_element, 010402 general chemistry, 01 natural sciences, Combinatorial chemistry, Catalysis, 0104 chemical sciences, Biomaterials, lcsh:Chemistry, lcsh:QD1-999, Reagent, enantioselectivity, nitriles­, titanium, Titanium
Abstract

International audience; The titanium-catalyzed asymmetric cyclopropanation of cyanoesters­ with Grignard reagents was investigated for the first time. Particularly, the study of the efficiency of Taddol-based titanium complexes­ has shown that the prior preparation of Taddol titanium complexes was not required and a large panel of ligands was evaluated by using this approach. The spirocyclopropanelactams were obtained with good diastereoselectivity and with moderate enantioselectivities from the main diastereoisomer (up to 32%).

Published
2018

5. Titanium-Mediated Addition of Grignard Reagents to Acyl Cyanohydrins: Aminocyclopropane versus 1,4-Diketone Formation

Author

Gwénaël Forcher, Philippe Bertus, Fabien Boeda, Paul Setzer, and Morwenna S. M. Pearson-Long

Subjects
Diketone, 010405 organic chemistry, Organic Chemistry, Grignard reaction, 010402 general chemistry, 01 natural sciences, 3. Good health, 0104 chemical sciences, Cyclopropane, chemistry.chemical_compound, chemistry, Reagent, Moiety, Organic chemistry, Reactivity (chemistry), Physical and Theoretical Chemistry, Titanium isopropoxide, Tetrahydrofuran
Abstract

The 1,2-dianion reactivity of the reagent generated from EtMgBr and titanium isopropoxide was illustrated when N-acyl cyanohydrins were used as substrates (>20 examples), giving both aminocyclopropane derivatives and 1,4-dicarbonyl compounds. When the reaction was performed in diethyl ether, 5-hydroxy-1,4-diketones were the main product. Under specific conditions (use of tetrahydrofuran and a bulky carboxylic moiety), the cyclopropane derivatives were obtained in good yields. The observed dichotomy may be explained by a ring-opening of the five-membered titanacycle intermediate followed by a nonselective acyl addition.

Published
2013

6. ChemInform Abstract: A Short Access to Symmetrically α,α-Disubstituted α-Amino Acids from Acyl Cyanohydrins

Author

Philippe Bertus, Florian Rouzier, Fabien Boeda, Julien Caillé, Houcine Ammar, Fatma Boukattaya, and Morwenna S. M. Pearson-Long

Subjects
chemistry.chemical_classification, chemistry, Stereochemistry, Reagent, Moiety, General Medicine, Chemoselectivity, Amino acid
Abstract

A straightforward synthesis of symmetrically α,α-disubstituted α-amino acids is presented. The key step of this process relies on the efficient double addition of Grignard reagents to acyl cyanohydrins to provide N-acyl amino alcohols selectively in good yields. The chemoselectivity of the reaction was modulated by the nature of the acyl moiety. Eleven amino acids were prepared, including the particularly simple divinylglycine, which is not easily accessible by using conventional methods.

Published
2016

7. Titanium-Mediated Synthesis of 1,4-Diketones from Grignard Reagents and Acyl Cyanohydrins

Author

Morwenna S. M. Pearson-Long, Alice Beauseigneur, Paul Setzer, Philippe Bertus, Unité de chimie organique moléculaire et macromoléculaire (UCO2M), Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), and ANR-07-BLAN-0283,SAAcoude,Aminoacides à conformation contrôlée: Nouvelles approches stéréosélectives et application à la conception de librairies de coudes beta(2007)

Subjects
[CHIM.ORGA]Chemical Sciences/Organic chemistry, 010405 organic chemistry, Chemistry, chemistry.chemical_element, General Medicine, General Chemistry, 010402 general chemistry, carbonyl compound, 01 natural sciences, Catalysis, grignard reagents, 3. Good health, 0104 chemical sciences, chemistry.chemical_compound, metallacycles, Reagent, synthetic methods, Organic chemistry, titanium, ComputingMilieux_MISCELLANEOUS, Cyanohydrin, Titanium
Abstract

The cyanohydrin substrates react with titanacyclopropanes, obtained in situ from Grignard reagents and Ti(OiPr)4, to produce 1,4-diketones.

Published
2010

8. Titanium-Catalyzed Cyclopropanation of Boc-Protected Cyanohydrins: A Short Access to Aminocyclopropanecarboxylic Acid Derivatives

Author

Jan Szymoniak, Alice Beauseigneur, Philippe Bertus, Philippe Karoyan, Morwenna S. M. Pearson-Long, Unité de chimie organique moléculaire et macromoléculaire (UCO2M), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Synthèse, Structure et Fonction de Molécules Bioactives (SSFMB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire de Reims - UMR 7312 (ICMR), Université de Reims Champagne-Ardenne (URCA)-Institut de Chimie du CNRS (INC)-SFR CAP Santé (Champagne-Ardenne Picardie Santé), Université de Reims Champagne-Ardenne (URCA)-Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)-SFR Condorcet, Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), SFR Condorcet, Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-SFR CAP Santé (Champagne-Ardenne Picardie Santé), and Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Université de Reims Champagne-Ardenne (URCA)-Université de Picardie Jules Verne (UPJV)-Université de Reims Champagne-Ardenne (URCA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
chemistry.chemical_classification, amino acids, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Chemistry, Cyclopropanation, Organic Chemistry, technology, industry, and agriculture, chemistry.chemical_element, Catalysis, organometallic reagents, Amino acid, Cyclopropane, chemistry.chemical_compound, cyclopropane, Organic chemistry, cyanohydrins, titanium, ComputingMilieux_MISCELLANEOUS, Titanium
Abstract

The preparation of protected 1-aminocyclopropanecarboxylic acid was performed from readily available and inexpensive start-ing materials, using titanium-catalyzed cyclopropanation as the key step. As an extension of this methodology, a diastereoselective synthesis of the cis-2-vinyl-substituted analogue is presented.

Published
2010

9. Chapter 7. Titanium-based Catalysts for Asymmetric Transformations

Author

Morwenna S. M. Pearson-Long, Philippe Bertus, and Fabien Boeda

Subjects
Nucleophile, Homogeneous, Ligand, Chemistry, Enantioselective synthesis, chemistry.chemical_element, Organic chemistry, Catalysis, Titanium
Abstract

Titanium is employed in a wide range of important enantioselective reactions, including epoxidations, reductions, nucleophilic additions, and cycloadditions. This chapter summarises the most important catalytic systems employed in these reactions and the sustainable aspects developed thereof. In particular, efforts to reduce the amount of catalyst (or the ligand) or the use of supported heterogeneous and homogeneous catalysts are described.

Published
2015

10. ChemInform Abstract: Titanium-Mediated Addition of Grignard Reagents to Acyl Cyanohydrins: Aminocyclopropane versus 1,4-Diketone Formation

Author

Philippe Bertus, Gwénaël Forcher, Fabien Boeda, Morwenna S. M. Pearson-Long, and Paul Setzer

Subjects
Diketone, chemistry.chemical_compound, chemistry, Reagent, Moiety, Reactivity (chemistry), General Medicine, Titanium isopropoxide, Diethyl ether, Medicinal chemistry, Tetrahydrofuran, Cyclopropane
Abstract

The 1,2-dianion reactivity of the reagent generated from EtMgBr and titanium isopropoxide was illustrated when N-acyl cyanohydrins were used as substrates (>20 examples), giving both aminocyclopropane derivatives and 1,4-dicarbonyl compounds. When the reaction was performed in diethyl ether, 5-hydroxy-1,4-diketones were the main product. Under specific conditions (use of tetrahydrofuran and a bulky carboxylic moiety), the cyclopropane derivatives were obtained in good yields. The observed dichotomy may be explained by a ring-opening of the five-membered titanacycle intermediate followed by a nonselective acyl addition.

Published
2014

11. ChemInform Abstract: Simple and Convenient Access to α,α,α-Trisubstituted Amides by Double Addition of Grignard Reagents to Acyl Cyanohydrins

Author

Houcine Ammar, Andrii Stanovych, Morwenna S. M. Pearson-Long, Fatma Boukattaya, Philippe Bertus, Souhir Abid, and Paul Setzer

Subjects
General method, Simple (abstract algebra), Chemistry, Reagent, General Medicine, Thiophene derivatives, Combinatorial chemistry
Abstract

A cheap, metal-free, and general method for the synthesis of the title compounds is presented.

Published
2012

12. Simple and convenient access to α,α,α-trisubstituted amides by double addition of Grignard reagents to acyl cyanohydrins

Author

Souhir Abid, Philippe Bertus, Paul Setzer, Fatma Boukattaya, Houcine Ammar, Morwenna S. M. Pearson-Long, Andrii Stanovych, Institut des Molécules et Matériaux du Mans (IMMM), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS), Unité de chimie organique moléculaire et macromoléculaire (UCO2M), Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Faculté des Sciences de Sfax, Université de Sfax - University of Sfax, Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), and Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)

Subjects
chemistry.chemical_classification, 010405 organic chemistry, Chemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Aryl, Metals and Alloys, Nucleophilic acyl substitution, General Chemistry, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, Catalysis, 3. Good health, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, chemistry.chemical_compound, Reagent, Materials Chemistry, Ceramics and Composites, Organic chemistry, [CHIM]Chemical Sciences, lipids (amino acids, peptides, and proteins), Alkyl, ComputingMilieux_MISCELLANEOUS
Abstract

The double addition of Grignard (alkyl, aryl, alkenyl, alkynyl) reagents to acyl cyanohydrins was performed under unusually smooth conditions with a concomitant O–N acyl transfer, providing a very simple and general access to α,α,α-trisubstituted amides.

Published
2012

13. ChemInform Abstract: Titanium-Mediated Synthesis of 1,4-Diketones from Grignard Reagents and Acyl Cyanohydrins

Author

Paul Setzer, Morwenna S. M. Pearson-Long, Alice Beauseigneur, and Philippe Bertus

Subjects
chemistry.chemical_compound, Chemistry, Reagent, Organic chemistry, chemistry.chemical_element, General Medicine, Cyanohydrin, Titanium
Abstract

The cyanohydrin substrates react with titanacyclopropanes, obtained in situ from Grignard reagents and Ti(OiPr)4, to produce 1,4-diketones.

Published
2011

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