Enantioselective sulfa-Michael addition of thioacids to α,β-unsaturated ketones with bifunctional organocatalyst

Rana, Nirmal K.; Unhale, Rajshekhar A.; Singh, Vinod K.

doi:10.1016/j.tetlet.2012.02.052

Cited by 26 publications

(18 citation statements)

References 54 publications

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“…Mass spectrometric and NMR data of 4−6 (Supporting Information) were in agreement with those previously reported. 24,25 3-Mercaptocycloalkanones. 3-Mercaptocycloalkanones 1−3 were obtained by enzyme-catalyzed hydrolysis of the respective 3acetylthiocycloalkanones 4−6.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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Analytical and Sensory Characterization of the Stereoisomers of 3-Mercaptocycloalkanones and 3-Mercaptocycloalkanols

Wakabayashi

Riegel

et al. 2020

J. Agric. Food Chem.

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3-Mercaptocycloalkanones and 3-mercaptocycloalkanols (chain lengths C5–C7) were obtained by addition of thioacetic acid to the respective 2-cycloalken-1-ones and subsequent enzyme-mediated hydrolysis and reduction with LiAlH4, respectively. The stereoisomers were separated via capillary gas chromatography using chiral stationary phases. Their configurations were determined based on 1H NMR data and enzyme-catalyzed kinetic resolutions. Odor thresholds and odor qualities were assessed by capillary gas chromatography/olfactometry. Compared to the analogous acyclic 4-mercapto-2-alkanones and 4-mercapto-2-alkanols, the cyclic polyfunctional thiols lacked fruity, tropical notes; the perceived odor properties ranged from cooked, roasted vegetables and meat types to onion-related notes. The odor thresholds of the enantiomers of the 3-mercaptocycloalkanones were mainly impacted by their ring size rather than their configuration. For the 3-mercaptocycloalkanols, the (S)-configuration at the stereogenic center bearing the thiol group and the relative configuration of the second asymmetric center with the hydroxyl group were of importance for low odor thresholds.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Mass spectrometric data and NMR data of 1−3 (Supporting Information) corresponded to those published in the literature. 24,25 3-Mercaptocycloalkanols. 3-Mercaptocycloalkanols 7−9 were prepared by reduction of the corresponding 3-acetylthiocycloalkanones 4−6 using LiAlH 4.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Analytical and Sensory Characterization of the Stereoisomers of 3-Mercaptocycloalkanones and 3-Mercaptocycloalkanols

Wakabayashi

Riegel

et al. 2020

J. Agric. Food Chem.

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“…For instance, access to enantiopure cyclopentane scaffolds linked through a sulfur atom can be facilitated (panel A) using reagent (−)-9 in high ee and yield as compared to designer catalytic systems. 66 In a similar vein, amine-based nucleophiles of all types can be appended (panel B). 67 Panel C shows how a low-yielding S N 2 reaction can be avoided to access chiral indole-linked systems.…”

Section: Strategic Application Of Stereospecific Strain Releasementioning

confidence: 99%

Strain-Release Heteroatom Functionalization: Development, Scope, and Stereospecificity

et al. 2017

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Driven by the ever-increasing pace of drug discovery and the need to push the boundaries of unexplored chemical space, medicinal chemists are routinely turning to unusual strained bioisosteres such as bicyclo[1.1.1]pentane, azetidine, and cyclobutane to modify their lead compounds. Too often, however, the difficulty of installing these fragments surpasses the challenges posed even by the construction of the parent drug scaffold. This full account describes the development and application of a general strategy where spring-loaded, strained C–C and C–N bonds react with amines to allow for the “any-stage” installation of small, strained ring systems. In addition to the functionalization of small building blocks and late-stage intermediates, the methodology has been applied to bioconjugation and peptide labeling. For the first time, the stereospecific strain-release “cyclopentylation” of amines, alcohols, thiols, carboxylic acids, and other heteroatoms is introduced. This report describes the development, synthesis, scope of reaction, bioconjugation, and synthetic comparisons of four new chiral “cyclopentylation” reagents.

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“…However, the difference in enantioselectivity ratio between p-nitrobenzaldehyde and benzaldehyde in the reaction with cyclohexanone could be due to an electron-withdrawing group; however, it is important to note the key role of strong hydrogen bonding between carboxylic acid and a nitro group, and a carbonyl group with an imidazol group to produce higher ee. 42 It seems that the side chain amine group of lysine has a signicant role in the transition state to enhance enantioselectivity. When the peptides 8aa(z) and 5aa were employed in the reaction between p-nitrobenzaldehyde and cyclohexanone as catalysts under dened conditions, the enantioselectivity reduced by 10% (Table 4, entries 3 and 4).…”

Section: Introductionmentioning

confidence: 99%

Rational design of mimetic peptides based on aldo-ketoreductase enzyme as asymmetric organocatalysts in aldol reactions

et al. 2014

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Enantioselective sulfa-Michael addition of thioacids to α,β-unsaturated ketones with bifunctional organocatalyst

Cited by 26 publications

References 54 publications

Analytical and Sensory Characterization of the Stereoisomers of 3-Mercaptocycloalkanones and 3-Mercaptocycloalkanols

Analytical and Sensory Characterization of the Stereoisomers of 3-Mercaptocycloalkanones and 3-Mercaptocycloalkanols

Strain-Release Heteroatom Functionalization: Development, Scope, and Stereospecificity

Rational design of mimetic peptides based on aldo-ketoreductase enzyme as asymmetric organocatalysts in aldol reactions

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