Stereochemical assignments of aldol products of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones by <sup>1</sup>H NMR

Erol, Sule; Doğan, İlknur

doi:10.1002/mrc.3813

Cited by 3 publications

(3 citation statements)

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“…Chiral compounds bearing thiazolidin-4-one ring have also been studied for their stereochemistry. Several studies have been done on these compounds regarding enantiodifferentiation of stereoisomers in the presence of chiral auxiliary [28], separation of enantiomers by chiral HPLC [29,30], and determination of absolute conformations [31,32].…”

Section: Introductionmentioning

confidence: 99%

Stereochemical Investigations of DiastereomericN-[2-(Aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides by Nuclear Magnetic Resonance Spectroscopy (1D and 2D)

Demir-Ordu

Demir-Dündar

Özkırımlı

2015

International Journal of Spectroscopy

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Some new N-[2-(aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides were synthesized and their structures were investigated by IR, NMR (1H, 13C, and 2D), and mass spectra. The presence of C-2 and C-5 stereogenic centers on the thiazolidinone ring resulted in diastereoisomeric pairs. The configurations of two stereogenic centers were assigned based upon 1H NMR analysis of coupling constants and 2D nuclear overhauser enhancement spectroscopy (NOESY) experiment. Resolution of the diastereoisomers was performed by high performance liquid chromatography (HPLC) using a chiral stationary phase.

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Section: Introductionmentioning

confidence: 99%

Stereochemical Investigations of DiastereomericN-[2-(Aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides by Nuclear Magnetic Resonance Spectroscopy (1D and 2D)

Demir-Ordu

Demir-Dündar

Özkırımlı

2015

International Journal of Spectroscopy

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“…Compounds 2 – 5 contain both a stereogenic center at C-5 of the heterocyclic ring and an axis of chirality [14] due to the hindered rotation around the N sp2 -C aryl bond and therefore exist as two diastereomeric pairs [13,15] (Scheme 2). The aldol reactions [16] of compounds 1 – 5 were carried out by treating the compounds with lithium diisopropyl amide (LDA) at −78 °C and followed by an electrophile quench with benzaldehyde (at −78 °C) (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Aldol Reactions of Axially Chiral 5-Methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones

Gunal

Doğan

2016

Molecules

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Axially chiral 5-methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones have been subjected to aldol reactions with benzaldehyde to produce secondary carbinols which have been found to be separable by HPLC on a chiral stationary phase. Based on the reaction done on a single enantiomer resolved via a chromatographic separation from a racemic mixture of 5-methyl-2-(α-naphthyl)imino-3-(α-naphthyl)-thiazolidine-4-one by HPLC on a chiral stationary phase, the aldol reaction was shown to proceed via an enolate intermediate. The axially chiral enolate of the thiazolidine-4-one was found to shield one face of the heterocyclic ring rendering face selectivity with respect to the enolate. The selectivities observed at C-5 of the ring varied from none to 11.5:1 depending on the size of the ortho substituent. Although the aldol reaction proceeded with a lack of face selectivity with respect to benzaldehyde, recrystallization returned highly diastereomerically enriched products.

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“…Stereogenic aldol units are, e.g., common in polyketides, which possess potent biological properties: the immunosuppressant FK506 [22], the anti-tumor agent discodermolide [23], and the antifungal agent amphotericin B [24] are three examples of such compounds with chiral aldol units. While earlier the synthesis of many such compounds was considered nearly impossible, modern aldol methodology has allowed for their efficient synthesis in many cases [25], supported for example by the application of NMR spectroscopy to understand mechanistic details [26][27][28]. One of the first organocatalysts for stereoselective aldol reactions was proline, as reported in the 1970s by groups at Schering AG and Hoffmann-La Roche [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Exploring Free Energy Profiles of Enantioselective Organocatalytic Aldol Reactions under Full Solvent Influence

Weiß

Brehm

2020

Molecules

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We present a computational study on the enantioselectivity of organocatalytic proline-catalyzed aldol reactions between aldehydes in dimethylformamide (DMF). To explore the free energy surface of the reaction, we apply two-dimensional metadynamics on top of ab initio molecular dynamics (AIMD) simulations with explicit solvent description on the DFT level of theory. We avoid unwanted side reactions by utilizing our newly developed hybrid AIMD (HyAIMD) simulation scheme, which adds a simple force field to the AIMD simulation to prevent unwanted bond breaking and formation. Our condensed phase simulation results are able to nicely reproduce the experimental findings, including the main stereoisomer that is formed, and give a correct qualitative prediction of the change in syn:anti product ratio with different substituents. Furthermore, we give a microscopic explanation for the selectivity. We show that both the explicit description of the solvent and the inclusion of entropic effects are vital to a good outcome—metadynamics simulations in vacuum and static nudged elastic band (NEB) calculations yield significantly worse predictions when compared to the experiment. The approach described here can be applied to a plethora of other enantioselective or organocatalytic reactions, enabling us to tune the catalyst or determine the solvent with the highest stereoselectivity.

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Stereochemical assignments of aldol products of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones by ¹H NMR

Cited by 3 publications

References 10 publications

Stereochemical Investigations of DiastereomericN-[2-(Aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides by Nuclear Magnetic Resonance Spectroscopy (1D and 2D)

Stereochemical Investigations of DiastereomericN-[2-(Aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides by Nuclear Magnetic Resonance Spectroscopy (1D and 2D)

Aldol Reactions of Axially Chiral 5-Methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones

Exploring Free Energy Profiles of Enantioselective Organocatalytic Aldol Reactions under Full Solvent Influence

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Stereochemical assignments of aldol products of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones by 1H NMR

Cited by 3 publications

References 10 publications

Stereochemical Investigations of DiastereomericN-[2-(Aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides by Nuclear Magnetic Resonance Spectroscopy (1D and 2D)

Stereochemical Investigations of DiastereomericN-[2-(Aryl)-5-methyl-4-oxo-1,3-thiazolidine-3-yl]-pyridine-3-carboxamides by Nuclear Magnetic Resonance Spectroscopy (1D and 2D)

Aldol Reactions of Axially Chiral 5-Methyl-2-(o-aryl)imino-3-(o-aryl)-thiazolidine-4-ones

Exploring Free Energy Profiles of Enantioselective Organocatalytic Aldol Reactions under Full Solvent Influence

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Stereochemical assignments of aldol products of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones by ¹H NMR