Synthesis and Chiral Recognition of Novel Regioselectively Substituted Amylose Derivatives

Kondo, S.; Yamamoto, Chiyo; Kamigaito, Masami

doi:10.1246/cl.2008.558

Cited by 28 publications

(26 citation statements)

References 10 publications

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“…Finally, the 6‐hydroxyl group was regenerated by the removal of the trityl group in a methanol/HCl mixture and reacted with R 2 NCO to form the corresponding carbamate. It should be pointed out that in this study triphenylmethyl chloride was used instead of 4‐methoxytriphenylmethyl chloride to selectively protect the 6‐hydroxyl group and both of them were effective to protect the 6‐hydroxyl group as trityl ether …”

Section: Resultsmentioning

confidence: 99%

“…In Table are summarized the chromatographic resolution results of racemates 2 – 9 on 1a – f using a conventional eluent, hexane/2‐propanol (90:10, v /v). Moreover, the data on the commercially available chiral column, Chiralpak AD, utilizing coated amylose tris(3,5‐dimethylphenylcarbamate) as chiral selector, which is regarded as one of the most useful CSPs, are included. Compared with Chiralpak AD, 1a – f showed higher chiral recognition abilities to racemates 2 and 7 .…”

Section: Resultsmentioning

confidence: 99%

“…Data taken from Ref. . The signs in parentheses represent the optical rotation of the first eluted enantiome.…”

Section: Resultsmentioning

confidence: 99%

“…The heterosubstituted polysaccharide derivatives having different substituents at 2, 3‐positions and 6‐position has also been obtained . However, the regioselective introduction of different substituents at 2‐ and 3‐positions was not achieved until 2008 . Based on the regioselective esterification at 2‐position of amylose reported by Dicke, two novel amylose derivatives with three different substituents at 2‐, 3‐, and 6‐positions have been successfully synthesized by the Okamoto group and they exhibited enantioseparation abilities comparable to or better than the commercial amylose‐based column, Chiralpak AD .…”

Section: Introductionmentioning

confidence: 99%

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Preparation and evaluation of regioselectively substituted amylose derivatives for chiral separations

et al. 2017

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Six novel regioselectively substituted amylose derivatives with a benzoate at 2-position and two different phenylcarbamates at 3- and 6-positions were synthesized and their structures were characterized by H nuclear magnetic resonance (NMR) spectroscopy. Their enantioseparation abilities were then examined as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) after they were coated on 3-aminopropyl silica gels. Investigations indicated that the substituents at the 3- and 6-positions played an important role in chiral recognition of these amylose 2-benzoate serial derivatives. The derivatives demonstrated characteristic enantioseparation and some racemates were better resolved on these derivatives than on Chiralpak AD, which is one of the most efficient CSPs, utilizing coated amylose tris(3,5-dimethylphenylcarbamate) as the chiral selector. Among the derivatives prepared, amylose 2-benzoate-3-(phenylcarbamate/4-methylphenylcarbamate)-6-(3,5-dimethylphenylcarbamate) exhibited chiral recognition abilities comparable to that of Chiralpak AD and may be useful CSPs in the future. The effect of mobile phase on chiral recognition was also studied. In general, with the decreased concentration of 2-propanol, better resolutions were obtained with longer retention times. Moreover, when ethanol was used instead of 2-propanol, poorer resolutions were often achieved. However, in some cases, improved enantioselectivity was achieved with ethanol rather than 2-propanol as the mobile phase modifier.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Data taken from Ref. . The signs in parentheses represent the optical rotation of the first eluted enantiome.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Preparation and evaluation of regioselectively substituted amylose derivatives for chiral separations

et al. 2017

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“…Recently, Zhang et al indicated that Brönsted acidic ILs can be used as a novel catalyst for the efficient acetylation of cellulose to onestep synthesize cellulose acetate with different DS and solubility. [23][24][25] However, the regioselective synthesis of cellulose esters is a complex and challenging work. 14 In physical organic chemistry, investigating the effect of substituents on the aromatic ring on the reaction rate is one of the most important methods to clarify the reaction process of esterication, alcoholysis, hydrolysis, etc.…”

Section: Introductionmentioning

confidence: 99%

Homogeneous benzoylation of cellulose in 1-allyl-3-methylimidazolium chloride: Hammett correlation, mechanism and regioselectivity

Chen

Feng

Zhang³

et al. 2015

RSC Adv.

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Homogeneous benzoylation of cellulose with a series of substituted benzoyl chlorides, in which substituents varied from electron donating to electron withdrawing groups, was investigated in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). The electronic effect of substituents had a considerable effect on the reaction. A plot of Hammett parameters of substituents vs. degree of substitution (DS) of resultant cellulose esters exhibited a V-shaped graph: a negative slope for negative Hammett parameters, and a positive slope for positive Hammett parameters. Such a Hammett plot indicated the mechanism of cellulose benzoylation: the reaction underwent a unimolecular ionization mechanism with a carbocationic intermediate when benzoyl chlorides were with electron-donating substituents, and a bimolecular addition-elimination mechanism with a tetrahedral intermediate when benzoyl chlorides were with electron-withdrawing substituents. In addition, 13 C-NMR analysis showed that most of the substituted benzoyl chlorides exclusively preferred the primary hydroxyl at the C-6 position. This unusually high regioselectivity was attributed to the synergistic effect of appropriate reaction rate, moderate steric effect and reaction mechanism of benzoylation.

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Solvent‐dependent conformation of a regioselective amylose carbamate: Amylose‐2‐acetyl‐3,6‐bis(phenylcarbamate)

et al. 2012

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Six amylose-2-acetyl-3,6-bis(phenylcarbamate) (AAPC) samples ranging in weight-average molar mass M(w) from 1.8 × 10(4) g mol(-1) to 1.1 × 10(6) g mol(-1) have been prepared from enzymatically synthesized amylose samples. Static light scattering, small-angle X-ray scattering, sedimentation equilibrium, and viscosity measurements were made for the samples in 1,4-dioxane (DIOX), 2-ethoxyethanol (2EE), and 2-butanone (MEK) all at 25°C to determine particle scattering functions, z-average radii of gyration, intrinsic viscosities, as well as M(w). The data were analyzed in terms of the wormlike cylinder model mainly to yield the helix pitch per residue h and the Kuhn segment length λ(-1), which corresponds to twice of the persistence length. The latter parameters (λ(-1)) in 2EE (11 nm) and MEK (12 nm) are quite smaller than those for amylose tris(phenylcarbamate) (ATPC) in the same solvent (16 nm in 2EE and 18 nm in MEK) whereas those for AAPC (21 nm) and ATPC (22 nm) in DIOX are essentially the same as each other. This indicates that the chain stiffness of AAPC is more strongly influenced by the solvents since the number of intramolecular H-bonds of AAPC is more changeable than that for ATPC.

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Synthesis and Chiral Recognition of Novel Regioselectively Substituted Amylose Derivatives

Cited by 28 publications

References 10 publications

Preparation and evaluation of regioselectively substituted amylose derivatives for chiral separations

Preparation and evaluation of regioselectively substituted amylose derivatives for chiral separations

Homogeneous benzoylation of cellulose in 1-allyl-3-methylimidazolium chloride: Hammett correlation, mechanism and regioselectivity

Solvent‐dependent conformation of a regioselective amylose carbamate: Amylose‐2‐acetyl‐3,6‐bis(phenylcarbamate)

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