Organocatalyst For Asymmetric Aldol Reaction Research Articles

Asymmetric aldol reactions in ketone/ketone systems catalyzed by ionic liquid-supported C2-symmetrical organocatalyst

Ionic liquid-supported (1S,2S)- and (1R,2R)-1,2-bis[(S)-prolinamido]-1,2-diphenylethanes act as organocatalysts in asymmetric aldol reactions of acetone with α-keto esters or trifluoroacetophenone providing high yields and from moderate to high enantioselectivity. Recycling of the catalyst with a gradual decrease in conversion and ee values is possible.

Low Catalyst Loading, Highly Efficient D-glucosamine-derived Organocatalysts for Asymmetric Aldol Reactions

Glucosamine as a kind of important nature chiral scaffold is widely regarded for its obvious advantages such as cheap, stable and readily available. In this communication, we reported the introduction of L-proline group at the amino functional group of D-glucosamine resulted in several efficient prolinamide organocatalysts, which could efficiently catalyze the asymmetric aldol reaction between acetone and various substituted benzaldehydes in the neat condition. Under the optimized conditions, 0.5 mol% of organocatalyst gave excellent chiral selectivity (83% ee value) with 88% yield, which was higher than that obtained using 10 mol% of organocatalyst. Keywords: Aldol reaction, asymmetric catalysis, carbohydrate, organocatalyst.

Hyperbranched polyethylene-supported l-proline: a highly selective and recyclable organocatalyst for asymmetric aldol reactions

A recyclable l-proline-based organocatalyst system with unique hyperbranched polyethylene as a scaffold is prepared for highly stereoselective asymmetric aldol reactions.

Green and Sustainable Heterogeneous Organo-Catalyst for Asymmetric Aldol Reactions

Linear amino acids covalently supported on graphene sheet were employed as catalysts for asymmetric aldol reactions between cyclohexanone and aldehydes (aliphatic and/or aromatic) in a batch type reactor in the presence of water. The reactions were found to exhibit high yield as well as excellent ee value. Additionally, the catalysts were found to be truly heterogeneous and eco-friendly.

ChemInform Abstract: Synthesis and Characterization of N‐Substituted (S)‐1,2,3,4‐Tetrahydroisoquinoline‐3‐carboxamides and Thioamides as Organocatalysts for Asymmetric Aldol Reaction.

AbstractTitle compounds (I) are synthesized and tested as catalysts for aldol reaction of nitrobenzaldehyde (II) with acetone.

Synthesis and Characterization of N-Substituted (S)-1,2,3,4-Tetrahydroisoquinoline-3-carboxamides and Thioamides as Organocatalysts for Asymmetric Aldol Reaction

Synthesis and Characterization of N-Substituted (S)-1,2,3,4-Tetrahydroisoquinoline-3-carboxamides and Thioamides as Organocatalysts for Asymmetric Aldol Reaction

Telaprevir fragments as organocatalysts in asymmetric direct aldol reactions of aldehydes

We have demonstrated that the fragments of Telaprevir can act as organocatalysts for asymmetric aldol reactions between aromatic aldehydes and acetone under mild conditions. The reaction conditions have been optimized in terms of the catalyst nature, choice of temperature, solvent, additive, and the catalyst loading. Under proper conditions, fairly good yield and enantioselectivity have been achieved.

ChemInform Abstract: Simple Ionic Liquid Supported C2‐Symmetric Bisprolinamides as Recoverable Organocatalysts for the Asymmetric Aldol Reaction in the Presence of Water.

C2-Symmetric (S)-prolinamides modified with ionic groups and bearing achiral diamine units were synthesized. Their potency as reusable organocatalysts for asymmetric aldol reactions of cycloalkanones or methyl ketones with aromatic (heteroaromatic) aldehydes in the presence of water was demonstrated. The 1,4-diaminobenzene-derived catalyst exhibited good catalytic performance and excellent recoverability over at least 15 reaction–regeneration cycles under the studied conditions.

ChemInform Abstract: Recent Applications of Organocatalysts in Asymmetric Aldol Reactions

AbstractReview: 120 refs.

Synthesis of sulphonated mesoporous phenolic resins and their application in esterification and asymmetric aldol reactions

Mesoporous phenolic resins were functionalized with sulphonic acid groups by four different types of sulphonation procedures: (i) direct sulphonation on the aromatic ring, (ii) alkyl sulphonation of the aromatic ring, and functionalizations of the phenolic hydroxyl surface by using an aryl silane, 2-(4-chlorosulphonylphenyl)ethyl trichlorosilane (iii) or a propyl silane, 3-mercaptopropyltrimethoxysilane (iv). The highest acidity loadings were obtained through direct sulphonation with fuming sulphuric acid (1.90 mmol H+ g−1) or chlorosulphonic acid (1.31 mmol H+ g−1) and these materials showed the highest conversion (97+ %) in Fischer esterification of acetic acid with propanol. However, the alkyl sulphonic groups, obtained through sulphonation procedure (ii) showed the highest stability in terms of maintenance of their acidity after use in consecutive catalytic runs or leaching treatments. This was demonstrated both through evaluation of the regenerated catalysts in a consecutive esterification run and during a leaching resistance test in aqueous medium. Moreover, the developed sulphonated mesoporous phenolic resins are presented as novel support for the non-covalent immobilization of an l-phenylalanine derived chiral diamine organocatalyst for asymmetric aldol reactions. The immobilization is established by an acid–base interaction between the sulphonic acid group and the amine function. The acidity and in particular the electronic withdrawing environment of the sulphonic acid groups influence enormously the catalytic performance of the non-covalent immobilized chiral diamine catalyst (aromatic > aliphatic).

Simple Ionic Liquid Supported C2‐Symmetric Bisprolinamides as Recoverable Organocatalysts for the Asymmetric Aldol Reaction in the Presence of Water

AbstractC2‐Symmetric (S)‐prolinamides modified with ionic groups and bearing achiral diamine units were synthesized. Their potency as reusable organocatalysts for asymmetric aldol reactions of cycloalkanones or methyl ketones with aromatic (heteroaromatic) aldehydes in the presence of water was demonstrated. The 1,4‐diaminobenzene‐derived catalyst exhibited good catalytic performance and excellent recoverability over at least 15 reaction–regeneration cycles under the studied conditions.

Basic chiral ionic liquids: A novel strategy for acid-free organocatalysis

We present design, synthesis and application of basic chiral ionic liquids based on commercially available (S)-proline. This new set of chiral ionic liquids was specifically designed to replace trifluoroacetic acid in enamine-based organocatalysis for asymmetric CC bond formation. Based on their permanent charge, these chiral ionic liquids could be applied as organocatalysts in asymmetric aldol reaction of 4-nitrobenzaldehyde and acetone, and good yields and selectivities up to 80%ee could be obtained without additional acid.

Polyvinylidene chloride supported L‐prolineamide as recoverable catalyst for asymmetric aldol reaction between ketone and aromatic aldehyde

AbstractA series of prolineamide modified by polyvinylidene chloride (PVDC) was synthesized and used as green recoverable organocatalysts for the asymmetric Aldol reactions between various ketones and aromatic aldehydes. The effects of solvent and catalyst dosage on the catalytic performances of as‐synthesized organocatalysts were investigated. It was found that as‐synthesized PVDC‐supported L‐prolineamides possessed good catalytic performance for the asymmetric Aldol reactions between cyclohexanone and a variety of aromatic aldehydes, affording high yields of up to 99%, excellent diastereoselectivities of up to above 8 : 92 d.r. value, and high enantioselectivities of up to above 92.3% e.e. value. In general, the catalytic performance of as‐synthesized organocatalysts closely depended on the catalyst dosage and solvent type as well. Particularly, as‐synthesized organocatalyst 1c, at a dosage of 5 mol % in 10 μL of water, exhibited high catalytic activity and stereoselectivity for the asymmetric Aldol reaction between cyclohexanone and p‐nitrobenzaldehyde at room temperature. In the meantime, it could be easily recovered and recycled, while the activity and enantioselectivity were nearly completely retained even after five cycles of recovery, showing promising application as an efficient green organocatalyst for the aforementioned asymmetric Aldol reactions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

ChemInform Abstract: (1R,2R)‐Bis[(S)‐prolinamido]cyclohexane Modified with Ionic Groups: The First C2‐Symmetric Immobilized Organocatalyst for Asymmetric Aldol Reactions in Aqueous Media.

AbstractCatalyst (I) can be recovered and reused at least 10 times without any decrease in the reaction rate or selectivity.

ChemInform Abstract: N‐Prolinylanthranilamide Pseudopeptides as Bifunctional Organocatalysts for Asymmetric Aldol Reactions.

AbstractVarious catalysts are investigated and it is found that modification of the structure by introducing a second stereogenic center improves the yields and the enantioselectivities.

ChemInform Abstract: Proline‐Based Dipeptides as Efficient Organocatalysts for Asymmetric Aldol Reactions in Brine.

AbstractSimple N‐proline‐based dipeptides (I) in combination with 2,4‐dinitrophenol produce the aldol products in high yields and with high diastereo‐ and enantioselectivities.

N-Prolinylanthranilamide Pseudopeptides as Bifunctional Organocatalysts for Asymmetric Aldol Reactions

Proline anthranilamide-based pseudopeptides were shown to be effective organocatalysts for enantioselective direct aldol reactions of a selection of aldehydes with various ketones with excellent yield, enantioselectivity up to 99% and anti to syn diastereoselectivity up to 25:1.

ChemInform Abstract: N‐Prolinylanthranilic Acid Derivatives as Bifunctional Organocatalysts for Asymmetric Aldol Reactions.

AbstractSeveral N‐prolinylanthranilic acid derivatives can be used as bifunctional organocatalysts in the direct asymmetric aldol reaction of cyclohexanone with aromatic aldehydes.

(1R,2R)‐Bis[(S)‐prolinamido]cyclohexane Modified with Ionic Groups: The First C2‐Symmetric Immobilized Organocatalyst for Asymmetric Aldol Reactions in Aqueous Media

AbstractThe first C2‐symmetric immobilized organocatalyst for asymmetric aldol reactions containing the (1R,2R)‐bis[(S)‐prolinamido]cyclohexane unit tagged with two imidazolium+/PF6– ion pairs has been synthesized. In its presence, (hetero)aromatic aldehydes reacted with linear or cyclic ketones in aqueous media to yield chiral aldols with high diastereo‐ and enantioselectivities and the catalyst could be recovered and reused at least 10 times without any decrease in the reaction rate or selectivity.

ChemInform Abstract: Glucosamine‐Based Primary Amines as Organocatalysts for the Asymmetric Aldol Reaction.

AbstractA number of glycosamines is prepared.