Synthesis and silica-based immobilization of monofunctionalized cyclomaltoheptaose derivatives for enantioselective HPLC

Dittmann, Helmutt; Scharwächter, Klaus; König, Wilfried Α.

doi:10.1016/s0008-6215(99)00280-3

Cited by 30 publications

(14 citation statements)

References 66 publications

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“…We were also able to resolve the N-containing cyclophanes successfully by micro-HPLC using selectively monofunctionalized cyclodextrin derivatives immobilized on silica. 28 The stereodynamic investigations of the 1,11-diaza [11] paracyclophanes by DCZE were performed in two series differing in the composition of the buffer as reaction medium. In the first series enantiomerizations were carried out in selector-free buffer zones, whereas the stopped-flow experiments in the second series were performed in cyclodextrin-containing buffers.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis, resolution, and investigation of the rotational interconversion process of atropisomeric 1,n‐diaza[n]paracyclophanes using cyclodextrin‐mediated capillary zone electrophoresis

et al. 2001

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A number of variously monosubstituted 1,n-diaza[n]paracyclophanes (n = 10-12), which show planar chirality and atropisomerism due to hindered rotation about single bonds, were synthesized via a classical route to analyze their stereodynamic properties. Racemic analytes with 10- and 11-membered bridges were resolved by capillary zone electrophoresis (CZE) in acidic phosphate buffers (pH 2.5-4.5) employing permethylated beta- and gamma-cyclodextrin as chiral additives. Moreover, cyclodextrin mediated CZE was used in a discontinuously driven mode for investigations of the rotational interconversion process of conformationally labile homologues (n = 11). In stopped-flow experiments, after baseline separation enantiomers were partially enantiomerized in situ inside the capillary by heating. The rate constants (k(enan) = 1/2 k(rac)) and rotational energy barriers (Delta G(++)) were determined from the resulting enantiomeric ratios. Energy barriers between 113-126 kJ/mol were found depending on the substituent of the benzene ring and the degree of ionization of the amino groups in bridgehead positions. The energy barriers increased in order of the substituents: NO(2) >> CF(3) > Br > Cl > CH(3) approximately F. In addition, the rotational energy barriers were decreased by approximately 6-8 kJ/mol in the presence of the chiral selector.

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Section: Resultsmentioning

confidence: 99%

“…28 The sign of the optical rotation was determined by chiroptically detection using a polarimeter with a flow cell from Knauer (Berlin, Germany). The (+)-enantiomer was eluted first and was obtained with an ee of about 79% (CZE).…”

Section: Preparative Enrichment Of (+)-And (−)-2-fluoro-111-diaza[11mentioning

confidence: 99%

Synthesis, resolution, and investigation of the rotational interconversion process of atropisomeric 1,n‐diaza[n]paracyclophanes using cyclodextrin‐mediated capillary zone electrophoresis

et al. 2001

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“…The first reaction sequence, adapted from a synthesis developed by König and co-workers, [36] started from 2 IϪVII ,3 IϪVII -tetradeca-O-methylcyclomaltoheptaose (1) Ϫ prepared in three steps from β-cyclodextrin by selective tertbutyldimethylsilylation at O-6, permethylation of the secondary hydroxy groups, and desilylation [46,47] Ϫ which was substituted regioselectively with an octenyl residue using sodium hydride and 8-bromo-1-octene in DMF, producing 2 IϪVII ,3 IϪVII -tetradeca-O-methyl-6 I -O-(oct-7-enyl)cyclomaltoheptaose (2) in 28% yield. After methylation of the residual 6-hydroxy groups, we obtained the desired 2 IϪVII ,3 IϪVII ,6 IϪVI -eicosa-O-methyl-6 I -O-(oct-7-enyl)cyclomaltoheptaose (4).…”

Section: Resultsmentioning

confidence: 99%

“…Thus, this approach allows only estimations of the purity and substitution pattern. [36,39,40] (ii) Selective synthesis by protecting-group chemistry, which takes advantage of the different reactivities and accessibilities of the hydroxy groups; those at the C-6 position are more reactive and often most nucleophilic, those at the C-2 position are the more acidic, and those at the C-3 position are the most inaccessible.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, NMR Spectroscopic Characterization and Polysiloxane‐Based Immobilization of the Three Regioisomeric Monooctenylpermethyl‐β‐cyclodextrins and Their Application in Enantioselective GC

Cousin¹,

Trapp

Peulon-Agasse³

et al. 2003

Eur J Org Chem

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2I−VI,3I−VII,6I−VII‐Eicosa‐O‐methyl‐2I‐O‐(oct‐7‐enyl)cyclomaltoheptaose, 2I−VII,3I−VI,6I−VII‐eicosa‐O‐methyl‐3I‐O‐(oct‐7‐enyl)cyclomaltoheptaose, and 2I−VII,3I−VII,6I−VI‐eicosa‐O‐methyl‐6I‐O‐(oct‐7‐enyl)cyclomaltoheptaose were synthesized by selective introduction of an oct‐7‐enyl group at one of the O‐2, O‐3, or O‐6 positions of selectively methylated cyclomaltoheptaose (β‐cyclodextrin, CD) and, depending on the synthetic route, by a subsequent permethylation step. Each of the regioisomeric mono‐oct‐7‐enylated permethylated β‐cyclodextrin derivatives was anchored by hydrosilylation to a hydridomethyldimethylsiloxane copolymer to yield unambiguously O‐2‐, O‐3‐, and O‐6‐bonded chiral stationary phases (CSP) of Chirasil‐Dex, which were evaluated in enantioselective gas chromatography (GC). O‐6‐Chirasil‐Dex displayed slightly inferior enantioselectivity relative to either O‐3‐ or O‐2‐Chirasil‐Dex. The statistical synthesis of the CSP by mono‐oct‐7‐enylation of β‐CD under varying reactions conditions (base, solvent), without the use of hydroxy group protection chemistry, furnished a mixture of O‐6‐ and O‐2‐Chirasil‐Dex in dimethylformamide and predominantly the O‐2‐regioisomer in dimethyl sulfoxide. Chirasil‐Dex, previously formulated exclusively as the O‐6 regioisomer, should be revised as an O‐2‐ and O‐6‐Chirasil‐Dex mixture. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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“…Therefore, almost all the b-CDs in the reported CSPs for HPLC are connected with the spacer arm at the primary hydroxyl position, or randomly connected at primary or secondary hydroxyl groups [4,5,12]. There are very few bonded stationary phase which involve the anchoring of b-CD at the secondary hydroxyl group position [13,14]. Recently, König [14] and co-workers reported a method to attach the spacers to one of the primary or secondary hydroxyl groups of b-CD to prepare CSPs for HPLC and micro-HPLC.…”

Section: Introductionmentioning

confidence: 99%

Application of naphthylcarbamate‐substituted β‐cyclodextrin bonded silica particles as stationary phase for high‐performance liquid chromatography

Gong

Lee²

2003

J of Separation Science

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Application of naphthylcarbamate-substituted b-cyclodextrin bonded silica particles as stationary phase for high-performance liquid chromatography Naphthylcarbamate-substituted (3-(2-O-b-cyclodextrin)-2-hydroxypropoxy)-propylsilyl-appended silica gel (NSCD-HPS) has been synthesized via a convenient liquidsolid phase reaction on a silica gel surface. The chromatographic behavior of NSCD-HPS in high-performance liquid chromatography (HPLC) was studied with several disubstituted benzenes and some chiral aromatic compounds under both normal and reversed-phase conditions. The results show that NSCD-HPS has excellent selectivity for the separation of positional isomers of disubstituted benzenes and enantiomers of chiral aromatic compounds.

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Synthesis and silica-based immobilization of monofunctionalized cyclomaltoheptaose derivatives for enantioselective HPLC

Cited by 30 publications

References 66 publications

Synthesis, resolution, and investigation of the rotational interconversion process of atropisomeric 1,n‐diaza[n]paracyclophanes using cyclodextrin‐mediated capillary zone electrophoresis

Synthesis, resolution, and investigation of the rotational interconversion process of atropisomeric 1,n‐diaza[n]paracyclophanes using cyclodextrin‐mediated capillary zone electrophoresis

Synthesis, NMR Spectroscopic Characterization and Polysiloxane‐Based Immobilization of the Three Regioisomeric Monooctenylpermethyl‐β‐cyclodextrins and Their Application in Enantioselective GC

Application of naphthylcarbamate‐substituted β‐cyclodextrin bonded silica particles as stationary phase for high‐performance liquid chromatography

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