Alternating chiral selectivity of aldol reactions under the confined space of mesoporous silica

2015 ◽  
Vol 51 (96) ◽  
pp. 17116-17119 ◽  
Author(s):  
Chewei Yeh ◽  
Yan-Ru Sun ◽  
Shing-Jong Huang ◽  
Yeun-Min Tsai ◽  
Soofin Cheng
Keyword(s):  
Mesoporous Silica ◽  
Aldol Reaction ◽  
Recyclable Catalyst ◽  
Aldol Reactions ◽  
Water Medium ◽  
Confined Space ◽  
Asymmetric Aldol ◽  
Co Catalysts ◽  
Asymmetric Aldol Reaction ◽  
Chiral Selectivity

The chiral selectivities were altered and high diastereo- and enantio-selectivities of the products were obtained in water medium without adding acid co-catalysts when a primary–tertiary diamine catalyst was immobilized on mesoporous SBA-15 to form a recyclable catalyst for the direct asymmetric aldol reaction of cyclohexanone with p-nitrobenzaldehyde.

scholarly journals New Mesoporous Silica-Supported Organocatalysts Based on (2S)-(1,2,4-Triazol-3-yl)-Proline: Efficient, Reusable, and Heterogeneous Catalysts for the Asymmetric Aldol Reaction

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4532
Author(s):  
Omar Sánchez-Antonio ◽  
Kevin A. Romero-Sedglach ◽  
Erika C. Vázquez-Orta ◽  
Eusebio Juaristi
Keyword(s):  
Mesoporous Silica ◽  
Heterogeneous Catalysts ◽  
Solid Phase ◽  
Aldol Reaction ◽  
Substantial Reduction ◽  
Catalytic Efficiency ◽  
Aldol Reactions ◽  
Catalytic Systems ◽  
Asymmetric Aldol ◽  
Asymmetric Aldol Reaction

Novel organocatalytic systems based on the recently developed (S)-proline derivative (2S)-[5-(benzylthio)-4-phenyl-(1,2,4-triazol)-3-yl]-pyrrolidine supported on mesoporous silica were prepared and their efficiency was assessed in the asymmetric aldol reaction. These materials were fully characterized by FT-IR, MS, XRD, and SEM microscopy, gathering relevant information regarding composition, morphology, and organocatalyst distribution in the doped silica. Careful optimization of the reaction conditions required for their application as catalysts in asymmetric aldol reactions between ketones and aldehydes afforded the anticipated aldol products with excellent yields and moderate diastereo- and enantioselectivities. The recommended experimental protocol is simple, fast, and efficient providing the enantioenriched aldol product, usually without the need of a special work-up or purification protocol. This approach constitutes a remarkable improvement in the field of heterogeneous (S)-proline-based organocatalysis; in particular, the solid-phase silica-bonded catalytic systems described herein allow for a substantial reduction in solvent usage. Furthermore, the supported system described here can be recovered, reactivated, and reused several times with limited loss in catalytic efficiency relative to freshly synthesized organocatalysts.

scholarly journals Straightforward Immobilization of Phosphonic Acids and Phosphoric Acid Esters on Mesoporous Silica and Their Application in an Asymmetric Aldol Reaction

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 249 ◽  
Author(s):  
Christian Weinberger ◽  
Tatjana Heckel ◽  
Patrick Schnippering ◽  
Markus Schmitz ◽  
Anpeng Guo ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Phosphoric Acid ◽  
Surface Area ◽  
Aldol Reaction ◽  
Synthesis Method ◽  
Mesoporous Silicas ◽  
Phosphonic Acids ◽  
Asymmetric Aldol ◽  
Asymmetric Aldol Reaction ◽  
Acid Esters

The combined benefits of moisture-stable phosphonic acids and mesoporous silica materials (SBA-15 and MCM-41) as large-surface-area solid supports offer new opportunities for several applications, such as catalysis or drug delivery. We present a comprehensive study of a straightforward synthesis method via direct immobilization of several phosphonic acids and phosphoric acid esters on various mesoporous silicas in a Dean–Stark apparatus with toluene as the solvent. Due to the utilization of azeotropic distillation, there was no need to dry phosphonic acids, phosphoric acid esters, solvents, or silicas prior to synthesis. In addition to modeling phosphonic acids, immobilization of the important biomolecule adenosine monophosphate (AMP) on the porous supports was also investigated. Due to the high surface area of the mesoporous silicas, a possible catalytic application based on immobilization of an organocatalyst for an asymmetric aldol reaction is discussed.

scholarly journals Development of fructose-1,6-bisphosphate aldolase enzyme peptide mimics as biocatalysts in direct asymmetric aldol reactions

RSC Advances ◽  
2021 ◽  
Vol 11 (58) ◽  
pp. 36670-36681
Author(s):  
Thabo Peme ◽  
Dean Brady ◽  
Wanyama Juma ◽  
Maya Makatini
Keyword(s):  
Aldol Reaction ◽  
Aldol Reactions ◽  
Peptide Mimics ◽  
Structural Motifs ◽  
Asymmetric Aldol ◽  
Asymmetric Aldol Reaction ◽  
Fructose 1,6 Bisphosphate

Novel asymmetric aldol reaction catalysing fructose-1,6-bisphosphate aldolase peptide mimics with secondary structural motifs.

Aerobic photooxidative direct asymmetric aldol reactions of benzyl alcohols using water as the solvent

RSC Advances ◽  
2015 ◽  
Vol 5 (49) ◽  
pp. 39539-39543 ◽  
Author(s):  
A. Fujiya ◽  
T. Nobuta ◽  
E. Yamaguchi ◽  
N. Tada ◽  
T. Miura ◽  
...  
Keyword(s):  
Aldol Reaction ◽  
Aldol Reactions ◽  
Asymmetric Aldol ◽  
Benzyl Alcohols ◽  
Asymmetric Aldol Reaction

We report an aerobic photooxidative direct asymmetric aldol reaction using water as the solvent.

Asymmetric aldol reaction organocatalyzed by bifunctional N-prolyl sulfinamides under solvent-free conditions

RSC Advances ◽  
2014 ◽  
Vol 4 (51) ◽  
pp. 26563-26568 ◽  
Author(s):  
Wen Wan ◽  
Wei Gao ◽  
Guobin Ma ◽  
Lei Ma ◽  
Fan Wang ◽  
...  
Keyword(s):  
Aldol Reaction ◽  
Solvent Free ◽  
Aldol Reactions ◽  
Matching Effect ◽  
Asymmetric Aldol ◽  
Solvent Free Conditions ◽  
Asymmetric Aldol Reaction

Chiral bifunctional N-prolyl sulfinamide and its TFA salts were synthesized and applied in asymmetric aldol reactions under solvent-free conditions. The aldol adducts were obtained with high to excellent yields, enantioselectivities and diastereoselectivities. A matching effect between chiral proline and sulfinamide moieties was observed for the catalysts.

scholarly journals Chiral Thiazolidine based Organocatalysts: Synthesis and Application in Asymmetric Aldol Reactions

2020 ◽  
Vol 17 (5) ◽  
pp. 372-380
Author(s):  
Ana Rita G. Félix ◽  
Pedro R.D. Simões ◽  
Francisco J.P.M. Sousa ◽  
M. Elisa Silva Serra ◽  
Dina Murtinho
Keyword(s):  
Reaction Time ◽  
Aldol Reaction ◽  
Aromatic Aldehydes ◽  
Aldol Reactions ◽  
Catalyst Loading ◽  
Reaction Parameters ◽  
Asymmetric Aldol ◽  
Asymmetric Aldol Reaction

Several novel chiral organocatalysts derived from thiazolidines containing amide and thioureia functionalities were synthesized in good yields. These organocatalysts were tested in the asymmetric aldol reaction of acetone with p-nitrobenzaldehyde. Reaction parameters such as reaction time, catalyst loading and solvent were optimized. Products with conversions up to 84% and enantiomeric ratios (er) up to 84.5:15.5 (R:S) were obtained. The effect of several chiral and non-chiral additives on the reactivity and selectivity of the reaction was also evaluated. The reaction was extended to other aromatic aldehydes with the best organocatalyst and when p-bromobenzaldehyde was used, an er of 94.5:5.5 (R:S) was obtained.

scholarly journals L-proline/cholesterol and diosgenin based thiourea cooperative system for the direct asymmetric aldol reaction in the presence of water

2020 ◽  
Vol 44 (5) ◽  
pp. 1278-1284
Author(s):  
Serkan EYMUR ◽  
Enis TAŞCI ◽  
Arzu UYANIK ◽  
Mustafa YILMAZ
Keyword(s):  
Aldol Reaction ◽  
Catalytic Efficiency ◽  
Aldol Reactions ◽  
Cooperative System ◽  
Asymmetric Aldol ◽  
Asymmetric Aldol Reaction ◽  
Hydrophobic Nature

A series of cholesterol and based hydrophobic urea and thiourea compounds were synthesized and successfully used as a cocatalyst for L-proline catalyzed aldol reactions in the presence of water. The anticonfigured products were obtained with good yields (up to 94%), high diastereoselectivities (up to 95:5), and high enantiomeric excesses (up to 93% ee). The successful results for catalytic efficiency of L-proline in the presence of water reveal the importance of the hydrophobic nature of cholesterol and diosgenin parts of thiourea on the reactivity and selectivity in the presence of water.

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