The aldol reaction, which is used by nature for the building for substrate recognition and can present suitably placed of carbohydrate molecules through the use of aldolase hydrophobic and hydrophilic regions, as true enzymes enzymes,1 is a most useful synthetic procedure for the operating in aqueous, biological systems also construction ...
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Solventfree asymmetric aldol reaction organocatalyzed by (S)prolinecontaining thiodipeptides under ballmilling conditions. JG Hernández, V GarcíaLópez, E Juaristi ... Efficient ballmill procedure in the 'green'asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water.
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Efficient mixing of all the components is accomplished by applying a mechanochemical technique (ball milling). The catalysis is air and moisture tolerant and can be performed with nonpurified...
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It has been recently shown1,2 that asymmetric direct aldol peptides supported on PEGPS resins have led only to low reactions can be efficiently carried out in water as the sole solvent3 using as catalysts proline derivatives that contain We thought that polystyrene (PS) could be a suitable large apolar groups and behave ...
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related work, Bolm and coworkers reported the asymmetric aldol reaction under solventfree conditions catalyzed by (S)proline (10 mol %) in a ball mill, using nearly stoichiometric amounts of ketone and aldehyde (:1). The antialdol products were obtained in high yields with up to 99% ee. In this study, Bolm and coworkers
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ChemInform Abstract: Efficient BallMill Procedure in the ′Green′ Asymmetric Aldol Reaction Organocatalyzed by (S)ProlineContaining Dipeptides in the Presence of Water. Article Sep 2011
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ChemInform Abstract: Efficient BallMill Procedure in the ′Green′ Asymmetric Aldol Reaction Organocatalyzed by (S)ProlineContaining Dipeptides in the Presence of Water. Article Sep 2011
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The organocatalytic activity of the methyl ester of (S)proline(S)phenylalanine, (S,S)2, in the asymmetric aldol reaction between cyclohexanone and acetone with various aromatic aldehydes under solventfree conditions in a ball mill has been evaluated. α,αDipeptide (S,S)2 catalyzed the stereoselective formation of the expected aldol products, with higher diastereo and ...
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Chiral Backbones: Highly Efficient Organocatalysts for Asymmetric Direct Aldol Reactions between Aromatic Aldehydes and Acylic Ketones ', J. Org. Che m. 2008, 73, .
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Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water José G. Hernández E. Juaristi Chemistry, Biology 2011 88 A Simple and Efficient Protocol for ProlineCatalysed Asymmetric Aldol Reaction
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The slow aldol reaction of cyclohexanone with pnitro benzaldehyde and the fast aamination of isovaleraldehyde with dibenzyl azodicarboxylate have been selected as model reactions for this study. Prospects and limitations of the disclosed continuousflow organocatalytic approach are widely discussed.
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Among such catalysts, lproline is the only known natural organocatalyst; it has been shown to catalyze asymmetric aldol reactions (33 ... Hernández JG, Juaristi E. Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water. Tetrahedron.
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The 1H NMR spectrum achiral diamine units and demonstrated their potency as of the 15fold regenerated catalyst was nearly identical to efficient catalysts in for asymmetric aldol reactions of that of the freshly prepared sample, which indicates that the ketones with aromatic (heteroaromatic) aldehydes in the operation period of catalyst 2b ...
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Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water ... A range of pyrrolidinede the ballmilling technique was mostefficient with a,adiphen rived organocatalysts were tested in the addition of aldehydes yl2pyrrolidinemethanol ...
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Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water. ... Highly Efficient Direct Asymmetric Aldol Reactions Catalyzed by a Prolinethioamide Derivative in Aqueous Media. European Journal of Organic Chemistry 2010, 2010 ...
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A new prolinamide derivative anchored to a polystyrene support has been straightforwardly prepared and employed as heterogeneous catalyst in the direct asymmetric aldol reaction with good results in terms of yield and stereoselectivity. The optimal reaction conditions were found when a 1:2 (v/v) water/chloroform mixture was used.
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We have developed direct asymmetric crossaldol reactions that can be performed in water without addition of organic solvents. A bifunctional catalyst with a long hydrophobic alkyl chain efficiently catalyzed the reactions and afforded the desired aldol products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor and acceptor was used. These ...
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Introduction The aldol reaction is one of the most powerful and best known CC forming synthetic reactions, universally present in basic and advanced organic chemistry texts and amply reviewed in organic synthetic books and series. 14 The reaction has industrial relevance either in bulk production, or in the fine chemical and pharmaceutical industry. 5 The aldol reaction has a particular ...
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Solventfree asymmetric aldol reaction organocatalyzed by (S)prolinecontaining thiodipeptides under ballmilling conditions. JG Hernández, V GarcíaLópez, E Juaristi ... Efficient ballmill procedure in the 'green'asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water.
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ChemInform Abstract: Efficient BallMill Procedure in the ′Green′ Asymmetric Aldol Reaction Organocatalyzed by (S)ProlineContaining Dipeptides in the Presence of Water. Article Sep 2011
WhatsApp: +86 18838072829![[PDF] Use of (R)Mandelic Acid as Chiral CoCatalyst in the Michael ...](/ktbo0xj/200.jpg)
This article describes a study on the Michael addition reaction of cyclohexanone to nitroolefins catalyzed by the chiral secondary amine (1S,4S)2tosyl2,5diazabicyclo[]heptane. Reactions were carried out under solventfree conditions to make them more environmentally friendly. Initially, the observed diastereoand enantioselectivities were moderate to good, but were significantly ...
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ChemInform Abstract: Efficient BallMill Procedure in the ′Green′ Asymmetric Aldol Reaction Organocatalyzed by (S)ProlineContaining Dipeptides in the Presence of Water. Article Sep 2011
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Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by ( S)prolinecontaining dipeptides in the presence of water. 2011 • ... these chiral ionic liquids could be applied as organocatalysts in asymmetric aldol reaction of 4 Available online 10 August 2012 nitrobenzaldehyde and acetone, and good yields ...
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A convenient, efficient, and general procedure for the synthesis of diaryl diselenides has been developed by the reaction of aryl diazonium tetrafluoroborates and potassium selenocyanate on the surface of alumina under ballmilling in the absence of any solvent, transition metal catalyst, and base in room temperature. A wide range of functionalized diaryl diselenides are obtained in high ...
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Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water José G. Hernández, Eusebio Juaristi Pages
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Efficient BallMill Procedure in the "Green" Asymmetric Aldol Reaction Organocatalyzed by (S)ProlineContaining Dipeptides in the Presence of Water Tetrahedron sept. de 2011 The organocatalytic activity of (S)prolinebased dipeptides 1ac has been evaluated in the asymmetric aldol reaction between representative ketones with various ...
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Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water. 2011 • ... The prolinecatalysed asymmetric aldol reaction is usually carried out in highly dipolar aprotic solvents (dimethylsulfoxide, dimethylformamide, acetonitrile) where proline ...
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A new efficient and highly recyclable organocatalyst has been developed for asymmetric crossaldol reactions under neat conditions in ketoneketone, ... Asymmetric aldol reaction of unmodified aldehydes with ketones catalyzed by 1(R),2(R)bis((S) ... Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S ...
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An efficient, solventfree ballmilling protocol for the asymmetric aldol reaction between cyclohexanone and cyclopentanone with various aromatic aldehydes using a novel series of (S)prolinecontaining dipeptides and thiodipeptides 1af as organocatalysts is general, (S)prolinecontaining thiodipeptides proved to be better organocatalysts relative to their analogous amides.
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The organocatalytic asymmetric aldol reaction via an in situ generated enamine intermediate is one of the most powerful synthetic tools to achieve enantiomerically pure products.
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The organocatalytic activity of (S)prolinebased dipeptides 1ac has been evaluated in the asymmetric aldol reaction between representative ketones with various aromatic aldehydes under solventfree 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 proceeded with good chemical ...
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Highly efficient asymmetric aldol reaction in brine using a fluorous sulfonamide organocatalyst. Organic Biomolecular Chemistry 2012, 10 ... Efficient ballmill procedure in the 'green' asymmetric aldol reaction organocatalyzed by (S)prolinecontaining dipeptides in the presence of water. Tetrahedron 2011, 67 ...
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