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  • 1
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; enantioseparation ; resolution ; chiral recognition ; high-performance liquid chromatography ; cellulose tris(3,5-dimethylphenylcarbamate) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) was coated on large-pore silica gels and used as a chiral stationary phase (CSP) for high-performance liquid chromatographic separation of enantiomers. The influences of pore size of silica gel, coating amount of CDMPC, coating solvent, and column temperature on chiral discrimination were investigated. CSPs prepared with a large-pore silica gel having a small surface area showed higher chiral recognition. The amount of CDMPC adsorbed on the silica gel influenced the chiral recognition of some racemates. Loading capacity of racemates increased with an increase of the amount of CDMPC supported on the silica gel, and a CSP coated with 45% CDMPC by weight can be used for both analytical and semi-preparative scale separations. The CDMPC, coated using acetone as the coating solvent, exhibited, in many cases, higher enantioselectivity than that obtained with tetrahydrofuran F as the coating solvent. © 1996 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0899-0042
    Keywords: enantioseparation ; chiral stationary phase ; HPLC ; amylose phenylcarbamate ; chiral discrimination ; resolution ; enantiomer ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four 4-halogen-substituted phenylcarbamate derivatives of amylose were prepared and their chiral recognition abilities as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) were evaluated and compared with those of the corresponding cellulose derivatives. The amylose derivatives with fluoro, chloro, bromo, or iodo group at the four-position on the phenyl group were found to show higher chiral resolving ability than the corresponding cellulose derivatives. Among four amylose derivatives 4-fluoro- and 4-chlorophenylcarbamates showed an excellent chiral recognition ability. Especially, amylose tris(4-chlorophenylcarbamate) resolved (±)-1,2,2,2-tetraphenylethanol with a very high α value (α = 8.29). In order to obtain useful information concerning the chiral recognition mechanism of this resolution, we also performed enantioseparation of a variety of analogous racemic alcohols, and found that both the hydroxy and bulky triphenylmethyl groups of the racemate are essential for the effective chiral recognition. Chirality 9:63-68, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 711-716 
    ISSN: 0899-0042
    Keywords: stereospecific polymerization ; chiral α-substituted acrylate ; stereoregularity ; chiroptical property ; isotactic polymer ; regular arrangement ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel chiral monomer, benzyl α-[(1-phenylethoxy)methyl]acrylate was synthesized, and the stereoregularity and chiroptical property of the polymers obtained by radical and anionic polymerizations were investigated. Anionic polymerization in toluene provided a polymer with high isotacticity regardless of optical purity of the monomer and difference of counter cations, Li+ and Mg2+, while radical polymerization appears to yield an atactic polymer. The isotactic copolymers anionically obtained from a mixture of (R)- and (S)-monomers showed peak splitting probably due to the triad arrangement of (R) and (S) groups of side chains in the resonance of 13C-NMR spectra. The isotactic polymer prepared from enantiomerically pure (R)-monomer ([α] 25 365 = +157°) with n-BuLi in toluene exhibited higher specific rotation ([α] 25 365 = +262°) than that of the radical polymer ([α] 25 365 = +162°). This may be explained by regular arrangement of optically active groups along the polymer chain of the isotactic polymer. Chirality 10:711-716, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0899-0042
    Keywords: chiral CE ; maltooligosaccharides ; cellooligosaccharides ; cis-diltiazem ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Twelve different disaccharides and a series of noncyclic malto- and cello-oligosaccharides were used as chiral selectors in capillary electrophoresis (CE). Most saccharides resolved the enantiomers of atropisomeric 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (BDHP) depending on the type (α or β) and position of the linkage between monosaccharides. The effect of chain length of malto- and cello-oligosaccharides on enantioseparation of BDHP was also investigated. The nature of cations in background electrolytes affected significantly the separation of BDHP enantiomers. Chirality 10:134-139, 1998. © 1998 Wiley-Liss,Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0899-0042
    Keywords: asymmetric polymerization ; stereospecific polymerization ; optically active polymer ; helix ; (+)-tartaric acid ; L-proline ; (+)-(S)-2-(1-pyrrolidinylmethyl)pyrrolidine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymerization of diphenyl-2-pyridylmethyl methacrylate was carried out with the complexes of organolithium compounds with 22 chiral ligands. Helix-sense-selectivity of the polymerization was largely affected by a slight structural difference of chiral ligands. (+)-(S)-2-(1-Pyrrolidinylmethyl)pyrrolidine was the most effective ligand in producing a one-handed helical polymer with narrow molecular weight distribution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 122-124 
    ISSN: 0899-0042
    Keywords: 4-acetoxy-2-azetidinone ; antibiotics ; carbapenem ; HPLC ; chiral stationary phases ; cellulose tris(1-phenylethylcarbamate) ; amylose tris(1-phenylethylcarbamate) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical resolution of six β-lactams was examined by HPLC using chiral stationary phases consisting of tris((R)-, (RS)-, and (S)-1-phenylethylcarbamate)s of cellulose and amylose. All β-lactams were optically resolved at least by one of the carbamates. Amylose tris((S)-1-phenylethylcarbamate) showed high optical resolving abilities for some β-lactams.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 616-621 
    ISSN: 0899-0042
    Keywords: cellulose tris(4-isopropoxyphenylcarbamate) ; cellulose tris(3,5-dimethyl-4-methoxyphenylcarbamate) ; amylose tris(3,5-dimethyl-4-methoxyphenylcarbamate) ; optical resolution ; HPLC ; chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ten phenylcarbamate derivatives of cellulose and amylose having alkoxy groups such as ethoxy, isopropoxy, and isobutoxy at 4-position, and methyl groups at 3- and 5-positions and methoxy group at 4-position were synthesized and their chiral recognition abilities as stationary phases for high-performance liquid chromatography were investigated and compared to those with tris(4-methoxyphenylcarbamate)s of cellulose and amylose. In 4-alkoxy derivatives of cellulose, chiral recognition ability increased as the bulkiness of 4-alkoxy groups increased. 4-Isopropoxy and 4-isobutoxy derivatives showed high chiral recognition. On the other hand, chiral discrimination of amylose 4-alkoxy derivatives scarcely depended on the bulkiness of the alkoxy group, and 4-methoxy and 4-isopropoxy derivatives showed high chiral recognition. 3,5-Dimethyl-4-methoxyphenylcarbamates of cellulose and amylose possessed higher chiral recognition ability than the corresponding 4-methoxy derivatives. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0899-0042
    Keywords: enantioseparation ; HPLC ; cyclodextrin ; phenylcarbamate ; chiral stationary phase ; optical resolution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New dichloro-, dimethyl-, and chloromethylphenylcarbamate derivatives of cyclodextrins (CDs) were prepared and their enantiomeric recognition abilities were evaluated as chiral stationary phases (CSPs) in normal phase high-performance liquid chromatography (HPLC). The effects of the type of cyclodextrins, the nature and position of the substituents on the phenyl ring, binding mode and spacer on the chiral recognition were studied in detail. No marked change of chiral recognition abilities was established by reversing the binding side of CDs (i.e., by the narrower [primary] opening of the cone-shaped CD to silica gel with the wider [secondary] opening sides). This result indirectly proves the previously drawn conclusion about the minor role of inclusion phenomena in chiral recognition in this case. Nevertheless, chiral recognition of these CSPs toward some compounds critically depends on the type of CDs used. All CD derivatives described in this study show rather low enantiomeric resolving abilities compared with corresponding polysaccharide (cellulose and amylose) derivatives, although very high enantioselectivity of separation was observed for a few compounds, such as racemic flavanone and cyclopropanedicarboxilic acid dianilide. © 1996 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0899-0042
    Keywords: optical resolution ; HPLC ; chromatography ; antiinflammatory drug ; ibuprofen ; ketoprofen ; flurbiprofen ; tiaprofenic acid ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct optical resolution of antiinflammatory drugs such as ibuprofen, ketoprofen, flurbiprofen, and tiaprofenic acid were attempted by high-performance liquid chromatography using tris(3,5-dimethylphenylcarbamate)s of cellulose and amylose as chiral stationary phases. Although ibuprofen was not sufficiently resolved, the other three 2-arylpropionic acids were completely resolved by amylose tris(3,5-dimethylphenylcarbamate). Ibuprofen was resolved as anilide derivative.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 13 (1992), S. 409-413 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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