Enantioselective Aldol Reactions of Aliphatic Aldehydes with Singh’s Catalyst

Kylmälä, Heli; Neuvonen, Antti; Jokela, Reija

doi:10.4236/ijoc.2013.32020

Cited by 4 publications

(2 citation statements)

References 31 publications

(31 reference statements)

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“…However, the self-aldol process occurred in less time compared to the cross-aldol reaction (Scheme 13). 17 Scheme 13 Self-aldol reactions of aliphatic aldehydes with Singh's catalyst (S,S)-1…”

Section: Scheme 12 Synthesis Of Functionalized Carbinols Using Singh'mentioning

confidence: 99%

Syntheses and Applications of Singh’s Catalyst

2020

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Singh’s catalyst has emerged as one of the most promising and valuable catalysts in the field of asymmetric synthesis. Since its discovery, it has proven to be one of the best organocatalysts for asymmetric direct aldol reactions, and is equally efficient in aqueous and organic media. In this Short Review, we summarize reactions utilizing Singh’s catalyst under various conditions.1 Introduction2 Synthesis of Singh’s Catalyst3 Applications in Asymmetric Synthesis4 Conclusion

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Section: Scheme 12 Synthesis Of Functionalized Carbinols Using Singh'mentioning

confidence: 99%

Syntheses and Applications of Singh’s Catalyst

2020

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“…19 At present aldol condensations are industrially mostly catalyzed using strong, homogeneous basic catalysts such as KOH, Ca(OH) 2 , or Na 2 CO 3 , or acidic catalysts such as (VO) 2 P 2 O 7 , niobic acid, MFI zeolites, etc. [20][21][22][23][24] Recent research focuses on hydrotalcite catalysts and other layered double hydroxides or functionalized silica materials as possible alternatives. 20 Among the various heterogeneous catalysts screened for aldol condensation reactions, silica-supported amines with acid and base active sites have shown outstanding catalytic performance.…”

Section: Introductionmentioning

confidence: 99%

Selective conversion of castor oil derived ricinoleic acid methyl ester into jet fuel

et al. 2016

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TiO₂-Catalyzed n-Valeraldehyde Self-Condensation Reaction Mechanism and Kinetics

Zhao

et al. 2017

ACS Catal.

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The mechanism of a TiO2-catalyzed n-valeraldehyde self-condensation reaction was first investigated using in situ Fourier transform–infrared spectroscopy (FT-IR) analysis. The result shows that the n-valeraldehyde molecule is adsorbed in two ways separately to Ti4+ and Ti–OH active sites: one involving a strong interaction between the surface Ti4+ and the carbonyl oxygen of n-valeraldehyde molecule, causing a red shift of ν(CO) and the other involving an interaction between the TiO2 surface hydroxyl group Ti–OH and the carbonyl oxygen of n-valeraldehyde molecule via a hydrogen bond, causing a significant shift of Ti–OH peaks to a lower wavenumber. On the basis of the in situ FT-IR analysis, a TiO2-catalyzed n-valeraldehyde self-condensation reaction mechanism was proposed. In the process of n-valeraldehyde adsorption, the infrared characteristic peaks of 2-propyl-3-hydroxyheptanal were not observed, indicating that the dehydration of 2-propyl-3-hydroxyheptanal to 2-propyl-2-heptenal proceeded very quickly. In the process of desorption of products, the infrared characteristic peaks of carboxylates were detected on the surface of TiO2, suggesting that n-pentanoic acid is generated in the reaction system. In addition, we speculate that n-pentanoic acid has a strong interaction with the surface of TiO2 and the generated carboxylates are hardly desorbed, leading to the deactivation of TiO2 catalyst. In order to get a better understanding of the process of TiO2-catalyzed n-valeraldehyde self-condensation, the liquid-phase reaction was monitored in real time by an in situ IR (React-IR). In the whole course of the reaction, 2-propyl-3-hydroxyheptanal was not detected, confirming that this intermediate cannot exist stably, not only on the TiO2 surface but also in the reaction liquid. In order to further verify the reaction mechanism and to confirm the rate-determining step, several possible Langmuir–Hinshelwood models were assumed. By the model identification, the Langmuir–Hinshelwood model with the surface reaction as the rate-determining step is found to be the most probable one.

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Enantioselective Aldol Reactions of Aliphatic Aldehydes with Singh’s Catalyst

Abstract: Aldols from aliphatic aldehydes had been synthesized enantioselectively using Singh's catalyst. Self and crossed aldol reactions with several linear aldehydes were performed.

Cited by 4 publications

References 31 publications

Syntheses and Applications of Singh’s Catalyst

Syntheses and Applications of Singh’s Catalyst

Selective conversion of castor oil derived ricinoleic acid methyl ester into jet fuel

TiO₂-Catalyzed n-Valeraldehyde Self-Condensation Reaction Mechanism and Kinetics

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Enantioselective Aldol Reactions of Aliphatic Aldehydes with Singh’s Catalyst

Abstract: Aldols from aliphatic aldehydes had been synthesized enantioselectively using Singh's catalyst. Self and crossed aldol reactions with several linear aldehydes were performed.

Cited by 4 publications

References 31 publications

Syntheses and Applications of Singh’s Catalyst

Syntheses and Applications of Singh’s Catalyst

Selective conversion of castor oil derived ricinoleic acid methyl ester into jet fuel

TiO2-Catalyzed n-Valeraldehyde Self-Condensation Reaction Mechanism and Kinetics

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Product

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TiO₂-Catalyzed n-Valeraldehyde Self-Condensation Reaction Mechanism and Kinetics