Solvent‐Free Asymmetric Organocatalysis in a Ball Mill ...
Solvent‐Free Asymmetric Organocatalysis in a Ball Mill Solvent‐Free Asymmetric Organocatalysis in a Ball Mill Rodríguez, Belén; Rantanen, Toni; Bolm, Carsten 2006-10-20 00:00:00 Milling around: Aldol and enantioselective anhydride opening reactions were effected in a ball mill under solvent‐free conditions to afford products in high yields and …
Asymmetric organocatalysis in a ball mill - TIB AV-Portal
In this video the authors present asymmetric organocatalyses performed in a ball mill. Three reaction types are being discussed: enantioselective aldol reactions, asymmetric Michael additions to nitro alkenes and dipeptide formations. In the laboratory the ball milling device is shown, and reaction details are revealed. Finally, future applications of mechanochemical …
N‐Heterocyclic Carbene Acyl Anion Organocatalysis by …
The ability to conduct N-heterocyclic carbene-catalysed acyl anion chemistry under ball-milling conditions is reported for the first time. This process has been exemplified through applications to intermolecular-benzoin, intramolecular-benzoin, intermolecular-Stetter and intramolecular-Stetter reactions including asymmetric examples and demonstrates that this …
Asymmetric Organocatalytic Reactions under Ball Milling ...
In particular, after in situ formation of the ligand by ball milling, metal salts (ZnO, Ni (OAc)2·4H2O or Cu (OAc)2·H2O) were added directly to the jar and milling continued for a …
Higher enantioselectivities in thiourea-catalyzed Michael ...
Potential for the use of ball milling in asymmetric organocatalysis has already been recognized. 12 Bolm and co-workers were the first to show that the aldol reaction can be performed under ball milling conditions using proline as a catalyst.13, 14 Other aldol reactions, operating via enamine activation, have then been described in the ball ...
Solvent-free asymmetric aldol reaction organocatalyzed …
An efficient, solvent-free ball-milling protocol for the asymmetric aldol reaction between cyclohexanone and cyclopentanone with various aromatic aldehydes using a novel series of (S)-proline-containing dipeptides and thiodipeptides 1a–f as organocatalysts is reported.In general, (S)-proline-containing thiodipeptides proved to be better organocatalysts …
(PDF) Mechanochemistry-Assisted Asymmetric Organocatalysis ...
In this regard, catalytic asymmetric synthesis. Beilstein J. Org. Chem. 2012, 8, 2132–2141. 2133. Scheme 1: Proline-catalysed aldol reaction in …
Organocatalytic solvent-free hydrogen bonding-mediated ...
1.5 equiv) were transferred to a clean, dry ball milling vessel loaded with 7.8 g3 of grinding balls. The vessel was placed in the micro mill and milling was started (milling cycle: 15 min of milling followed by a 15 minutes pause). The mixture was obtained by washing the vessel and the balls with 3 x 3-5 mL of DCM or EtOAc.4 The
The Ion Tag Strategy as a Route to Highly Efficient ...
José G. Hernández, Eusebio Juaristi, Efficient ball-mill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)-proline-containing dipeptides in the presence of water, Tetrahedron, 10.1016/j.tet.2011.06.042, 67, 36, (6953-6959), (2011).
Fundamentals and Prospects of Catalysis
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Hot Topic: Organocatalysis
Asymmetric photocatalysis: This review provides a current overview of visible-light-induced asymmetric photocatalysis enabled by chiral organocatalysts.Innovative approaches including mono- and dual-catalysis are discussed. Chiral organocatalysis such as enamine catalysis, iminium-ion catalysis, Brønsted acid/base catalysis, and N-heterocyclic …
(PDF) Solvent-free asymmetric aldol reaction ...
Furthermore, the enantiomeric excesses in aldol product 6a were ndez et al. / Tetrahedron 68 (2012) 92e97 J.G. Herna 95 MeO O Table 3 S Scope of the direct asymmetric aldol reaction of cyclic ketones with various alde- N hydes catalyzed by (S,S)-1d under ball-milling conditionsa H O O O OH N O NO2 7 mol% (S,S)-1d +H R R + syn isomer Ball ...
Mechanochemical Organocatalysis: Do High ...
N-Heterocyclic Carbene Acyl Anion Organocatalysis by Ball-Milling. Nicholson WI, Seastram AC, Iqbal SA, Reed-Berendt BG, Morrill LC, Browne DL. ChemSusChem, 13(1):131-135, 27 Nov 2019 Cited by: 1 article | PMID: 31774627 | …
Green Chemistry Meets Asymmetric Organocatalysis: A ...
Design of potential peptide catalysts and synthesis of Juaristi catalyst 1n for the neat aldol reaction under ball milling conditions (iBBCl= isobutyl chloroformate, NMM= 4‐methylmorpholine). Being inspired by Type I aldolases, it is not surprising that the aldol reaction was the first transformation on which peptide organocatalysts were tested.
efficient ball mill croydon
Efficient ball-mill procedure in the 'green' asymmetric ... The organocatalytic activity of (S)-proline-based dipeptides 1a–c has been evaluated in the asymmetric aldol reaction between representative ketones with various aromatic aldehydes under solvent-free conditions in a ball mill.In particular, the methyl ester of (S)-proline-(S)-tryptophan, (S,S)-1c, proved to be an …
Solvent-Free Asymmetric Anhydride Opening in a Ball Mill ...
The mechanochemical technique of ball milling has been applied to the asymmetric opening of meso-anhydrides, mediated by the cinchona alkaloid quinidine. A simple workup procedure affords the products, optically active dicarboxylic acid monoesters, in high yields, with up to 64% ee. With most substrates no column chromatography was needed. A …
Green Asymmetric Organocatalysis | Request PDF
Asymmetric organocatalysis is becoming one of the main tools for the synthesis of chiral compounds that are needed as medicines, crop protection agents, and …
Solvent-Free Asymmetric Organocatalysis in a Ball Mill ...
Request PDF | Solvent-Free Asymmetric Organocatalysis in a Ball Mill | (Chemical Equation Presented) Milling around: Aldol and enantioselective …
Recent efforts directed to the development of more ...
Scheme 18 Asymmetric aldol reaction catalyzed by dipeptides 23 and 24 under ball-milling conditions. In more recent work, Hernández and Juaristi reported the asymmetric aldol reaction between ketones and various aromatic aldehydes under solvent-free conditions in a ball mill, with organocatalysis by several ( S )-proline-containing dipeptides.
N-Sulfinylpyrrolidine-containing ureas and thioureas as ...
Under ball-milling conditions, the Michael adducts were obtained in good yields but with slightly lower enantiomeric purities than in solution. DFT calculations elucidated its mode of action and confirmed a dual activation mode, which combines enamine activation of aldehydes and hydrogen-bond activation of nitroalkenes.
Research | Prof. Dr. Carsten Bolm
Subsequently, the Bolm group extended the research program to organocatalysis, where the initially studied asymmetric desymmetrization of meso-anhydrides was rapidly extended to very many other catalytic applications of purely organic molecules. In 2014, Bolm was the first to perform asymmetric organocatalysis in a ball mill, and this ...
Solvent‐Free Asymmetric Organocatalysis in a Ball Mill ...
Milling around: Aldol and enantioselective anhydride opening reactions were effected in a ball mill under solvent-free conditions to afford products in high yields and with high enantioselectivities after short reaction times (see scheme).
Efficacy of Selenourea Organocatalysts in Asymmetric ...
An alternative approach investigated the mechanochemical effects induced by ball-milling in the above selenourea-catalyzed asymmetric Michael–hemiacetalization reaction.
Mechanochemistry assisted asymmetric organocatalysis: A ...
Ball-milling and pestle and mortar grinding have emerged as powerful methods for the development of environmentally benign chemical transformations. Recently, the use of these mechanochemical techniques in asymmetric organocatalysis has increased. This ...
Asymmetric Synthesis & Catalysis Research Group
The organocatalysis can be merged with photo- and electrocatalysis to develop the synergistic catalytic transformations. We are also doing asymmetric domino/cascade reactions for the stereo-controlled formation of multiple stereogenic centres. We are also interested in organic synthesis through mechano-chemical methods such as ball-milling.
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S2 Detailed procedure for the solvent-free anhydride-opening in the ball mill Preparation of (2R,3S)-3-endo-(4-methyl-benzyloxycarbonyl)-bicyclo[2.2.1]hept-5-ene-2- endo-carboxylic acid (3); A clean, dry ball milling vessel was charged with 60 zirconium oxide grinding balls, the anhydride 1 (1.0 mmol), quinidine (1.1 equiv) and alcohol 2 (1.0 equiv). The vessel was …
Mechanochemistry assisted asymmetric organocatalysis: A ...
viz. ball-milling and grinding with pestle and mortar. Review Aldol reaction Since the origin of organocatalysis, the asymmetric aldol reac-tion has been one of the most intensely studied reactions, providing an easy access to chiral β-hydroxycarbonyl com-pounds, which are important building blocks for various bioac-tive molecules [28].
Mechanochemistry assisted asymmetric organocatalysis: A ...
Ball-milling and pestle and mortar grinding have emerged as powerful methods for the development of environmentally benign chemical transformations. Recently, the use of these mechanochemical techniques in asymmetric organocatalysis has increased.
Efficient ball-mill procedure in the 'green' asymmetric ...
The organocatalytic activity of (S)-proline-based dipeptides 1a–c has been evaluated in the asymmetric aldol reaction between representative ketones with various aromatic aldehydes under solvent-free conditions in a ball mill.In particular, the methyl ester of (S)-proline-(S)-tryptophan, (S,S)-1c, proved to be an efficient organocatalyst, and the aldol reaction …
Recent Advances in Sustainable Organocatalysis | IntechOpen
The recent advances on green and sustainable organocatalysis are revised in this chapter. An important focus on one of the 12 principles of green chemistry, organocatalysis pursues to reduce energy consumption as well as to optimize the use of different resources, targeting to become a sustainable strategy in organic chemical transformations.