A convenient route to optically active γ-substituted γ-lactones

Karnik, Anil V.; Patil, Sudhir T.; Patnekar, Subodh S.; Semwal, Abha

doi:10.1039/b409061f

Cited by 13 publications

(12 citation statements)

References 20 publications

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“…The tripodal receptors with two phenylglycinol-derived oxazolines displayed significant enantioselectivity for racemic α-chiral ammonium ions (Table 23, entries [1][2][3][4][5][6][7][8]. It was revealed that the changing receptor's symmetry, from C 3 to C 1 , causes intense improvement in the binding mode and chiral recognition.…”

Section: Entrymentioning

confidence: 99%

“…Various biological phenomena such as enzyme-substrate, antibody-antigen and drug-biomolecule interactions are a manifestation of the importance of enantiospecific supramolecular processes in living organisms [4]. The importance of chirality in the fields of medicine [5,6], asymmetric synthesis, [7,8] catalysis [9], flavor [10], fragrances [11], biochemistry [12] and material science chemistry [13] has already been well established. While the area of asymmetric synthesis has witnessed a tremendous growth, the practicality of preparing homochiral compounds still remains a challenge.Thus, the stimulus for interest in the separation of racemic mixtures exploiting host-guest chemistry has gained popularity over the years.…”

Section: Introductionmentioning

confidence: 99%

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Chiral Heterocycle-Based Receptors for Enantioselective Recognition

et al. 2018

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Abstract:The majority of biomolecules found in living beings are chiral, therefore chiral molecular recognition in living systems is crucial to life. Following Cram's seminal work on the crown-based chiral recognition, prominent research groups have reported innumerable chiral receptors with distinctly different geometrical features and asymmetry elements. Main applications of such chiral receptors are found in chiral chromatography, as for analytical purposes and for bulk separation of racemates.Incorporation of heterocyclic rings in these recognition systems added a new dimension to the existing group of receptors. Heterocycles have additional features such as availability of unshared electron pairs, pronounced conformational features, introduction of hydrogen bonding and presence of permanent dipoles as well as specific spectral properties in certain cases. These features are found to enhance binding properties of the receptors and the selectivity factors between opposite enantiomers, allowing them to be effectively separated. The review presents the synthetic approaches towards these heterocyclic receptors and their distinctly different behavior vis-à-vis carbocyclic receptors.

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Section: Entrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chiral Heterocycle-Based Receptors for Enantioselective Recognition

et al. 2018

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“…42 Optically active γ-substituted γ-lactone synthesis was reported by Karnik et al from ( S )-menthyl or ( S )-bornyl esters of 4-carboxylates by sodium borohydride reduction with very moderate yield and enantioselectivity of ( S )-GVL. 39 Enzymatic reduction often results in excellent enantioselectivity of the products. Hilterhaus et al investigated a chemoenzymatic reduction reaction of LA to obtain ( S )-GVL in good yields and ee (∼90%).…”

Section: Introductionmentioning

confidence: 99%

Room-Temperature Asymmetric Transfer Hydrogenation of Biomass-Derived Levulinic Acid to Optically Pure γ-Valerolactone Using a Ruthenium Catalyst

et al. 2019

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This study presents a first report on ruthenium-catalyzed asymmetric transfer hydrogenation (ATH) of levulinic acid (LA) to chiral γ-valerolactone (GVL). ATH of LA has been explored with Noyori’s chiral catalyst (Ru–TsDPEN) in methanol solvent. Efficacy of ATH reaction of LA was investigated under different reactions conditions such as temperature, catalyst, and hydrogen donor concentration. The effect of various organic tertiary bases along with formic acid (FA) as a hydrogen donor was studied, and N-methylpiperidine with FA (1:1 molar ratio) was revealed as an efficient hydrogen donor for ATH of LA to GVL furnishing chiral GVL with complete conversion and 93% enantiomeric excess (ee). This operationally simple and mild ATH protocol was tested for practical applicability of ATH of LA obtained from biomass waste (rice husk and wheat straw) and furnished chiral GVL with 82% ee.

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“…Karnik et al reported the stoichiometric synthesis of optically active γ--lactones from (S)--menthyl or (S)--bornyl esters of 4--carboxylates by using NaBH 4 , however, the yield of (S)--GVL was moderate. 26 Hilterhaus et al suggested a chemoenzymatic reaction sequence to produce (S)--GVL via ethyl levulinate (EL). Expectedly, due to the enzymatic conversion, the ee values and overall yields were high (~90%).…”

Section: Introductionmentioning

confidence: 99%

Direct asymmetric reduction of levulinic acid to gamma-valerolactone: synthesis of a chiral platform molecule

et al. 2015

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Levulinic acid was directly converted to optically active (S)--gamma--valerolactone, a proposed biomass--based chiral platform molecule. By using SEGPHOS ligand--modified ruthenium catalyst in methanol as co--solvent, eventually, 100% chemoselectivity, and 82% enantioselectivity were achieved. The effect of catalyst composition and reaction parameters on the activity and selectivity were investigated in details. The conversion of a "real" biomass derived levulinic acid to optically active GVL without decreasing the enantioselectivty was also demonstrated.

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A convenient route to optically active γ-substituted γ-lactones

Cited by 13 publications

References 20 publications

Chiral Heterocycle-Based Receptors for Enantioselective Recognition

Chiral Heterocycle-Based Receptors for Enantioselective Recognition

Room-Temperature Asymmetric Transfer Hydrogenation of Biomass-Derived Levulinic Acid to Optically Pure γ-Valerolactone Using a Ruthenium Catalyst

Direct asymmetric reduction of levulinic acid to gamma-valerolactone: synthesis of a chiral platform molecule

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