Synthesis and Properties of 6A-Amino-6A-deoxy-α and β-cyclodextrin

Brown, SE; Coates, John H.; Coghlan,; Easton, CJ; Vaneyk, SJ; Janowski, WK; Lepore, Anna L.; Lincoln, SF; Luo, Yu; May, Bruce L.; Schiesser, DS; Wang, P; Williams, M.

doi:10.1071/ch9930953

Cited by 66 publications

(30 citation statements)

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“…A -deoxy-b-cyclodextrin (9) [79] and cinnamaldehyde (8, Scheme 2). It was anticipated that the imine 10 would form reversibly and that, with the cyclodextrin attached, it might be more reactive than the free aldehyde 8.…”

Section: Resultsmentioning

confidence: 99%

Reversal of Regioselectivity and Enhancement of Rates of Nitrile Oxide Cycloadditions through Transient Attachment of Dipolarophiles to Cyclodextrins

Barr

Lincoln

Easton

2006

Chemistry A European J

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The reactions of nitrile oxides with monosubstituted dipolarophiles, such as propiolamide, typically afford proportionally 80 % or more of the 3,5-disubstituted cycloadducts. By contrast, the reactions of 6(A)-deoxy-6(A)-propynamido-beta-cyclodextrin with 4-tert-butylbenzonitrile oxide and 4-phenylbenzonitrile oxide afford >90 % and approximately 85 % of the corresponding 3,4-disubstituted isoxazoles, respectively. As well as reversing the regioselectivity, the cyclodextrin increases the rates of these cycloadditions. The extent of the acceleration is up to more than three orders of magnitude for the production of the cycloadduct preferred by the cyclodextrin, but even the rate of reaction to give the less favored regioisomer is increased. With 6(A)-deoxy-6(A)-propynamido-beta-cyclodextrin, the cycloadducts are not easily separated from the cyclodextrin, as the amide bond is not readily cleaved. In comparison, the regioselectivity of the cycloadditions of 4-tert-butylbenzonitrile oxide with acrylic acid, methacrylic acid, and crotonic acid is also altered by formation of the corresponding cyclodextrin esters, by factors of 500, >10, and >100, respectively. The rates of cycloaddition are also increased by up to 475 times, and in these cases the products of cycloaddition are readily released from the cyclodextrin through ester hydrolysis. Incorporating these processes into a reaction cycle, acylation of beta-cyclodextrin with p-nitrophenyl acrylate and subsequent treatment first with 4-tert-butylbenzonitrile oxide and then with base, the latter to catalyze ester hydrolysis and regenerate the beta-cyclodextrin, affords proportionally fivefold more of the 3,4-disubstituted isoxazoline than is produced directly from acrylic acid.

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Section: Resultsmentioning

confidence: 99%

Reversal of Regioselectivity and Enhancement of Rates of Nitrile Oxide Cycloadditions through Transient Attachment of Dipolarophiles to Cyclodextrins

Barr

Lincoln

Easton

2006

Chemistry A European J

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“…This consideration is based on the fact that the amino group attached at the CD rim has a lower pKa value (approximately 7). 10,11,14,15 Thus, we assume that pKa1 of 3 corresponds to the protonation equilibrium of the ζ-amino group. Accordingly, the β-amino group's deprotonation occurs above pH 8.…”

Section: Resultsmentioning

confidence: 99%

Pyrene-appended α-Cyclodextrin as a Fluorescent pH Probe Responding to a Wide Range

Suzuki

Yamauchi

2006

ANAL. SCI.

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The design of probe molecules showing photometric and fluorescent signals to target analytes is a currently important topic for fueling further developments of molecular biology and material sciences. Among the probe molecules, pH indicators such as methyl orange and phenolphthalein have long been used to visualize the pH of a solution. Determining the pH by probe molecules is also currently intriguing the attention of chemists. In particular, fluorescent probe molecules responding to pH have been extensively explored because of their high sensitivity and applicability to imaging purposes. [1][2][3][4] The design of fluorescent pH probes is based on coupling aromatic molecules with amine or other dissociable functionalities. Thus, the working pH range of fluorescent pH probes must relate to the pKa values of the dissociable functionalities. This, however, implies an intrinsic drawback of fluorescent and photometric pH probes. Since the signals of pH probes are dependent solely on the protonation equilibrium, the expected pH range is limited to be pKa ± 1. To overcome this drawback, the introduction of additional protonation sites on the probe molecules may be effective. [5][6][7][8][9] In general, however, the additional protonated sites may not function well, because either of the protonated equilibria mostly controls the fluorescence signals, and because the two pKa values tend to separate largely from each other. As shown in Fig. 1, an ideal fluorescent pH probe functioning over a wide pH range should have 2 units of a pKa difference (∆pKa), with each protonation step equally contributing to the observable fluorescence signals.Recently, we have found that cyclodextrins (CDs) bearing a pyrenylmethylamino group (1 and 2) had pKa values of around 7, 10,11 which was substantially lower than the pKa values of normal amines, with large fluorescence intensity changes due to photo-induced electron transfer (PET) from the amino groups to the excited pyrene residues. 12 These results prompted us to construct a novel fluorescence pH probe functioning over a wide pH range by introducing an additional amino group with an appropriate alkyl spacer. Based on this strategy, we prepared a novel fluorescent α-CD derivative with a trimethylenediamine linker (3). In this communication, we report that 3 shows unique fluorescence properties satisfying the prerequisites for an ideal fluorescent pH probe functioning over the wide pH range of 5 -10. ExperimentalThe synthesis of 3 was performed in a similar manner to obtain

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“…These steps are almost quantitative with yield higher than 90%. Our approach has greatly improved with mild reaction conditions and higher yields than previously reported methods, i. e. one by nucleophilic displacement of tosyl group with ammonia under pressure (10 6 N m -2 ) for 18 h at room temperature [38], another by azide substitution of CD tosylate and a following hydrogenation with Pd/C for 12 h [39]. Both procedures are low yielding and incomplete reactions, thus undesirable for large-scale production.…”

Section: Overview Of Synthetic Approaches To Monosubstituted Cationicmentioning

confidence: 95%

“…The degree of inclusion of analyte into CD cavity and the degree of enantioselectivity can both be altered by the nature of surrounding solvent system [38]. CDs are often thought to act via the inclusion of a non-polar portion of the guest molecule inside their hydrophobic cavity.…”

Section: Addition Of Organic Solvent In Chiral Cementioning

confidence: 99%

Monosubstituted positively charged cyclodextrins: Synthesis and applications in chiral separation

Tang

Ng²

2008

J of Separation Science

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Several series of novel structurally well-defined positively charged CDs, applicable to alpha-, beta- and gamma-CDs for chiral separation using CE and chromatographic techniques have been developed. The chiral resolution capabilities of different series CDs towards amino acids and anionic analytes in CE are systematically investigated by considering all separation parameters including CD type, alkyl chain length of the cations attached to the CD rim, CD concentration, buffer pH, separation temperature and organic solvent. Typical results are demonstrated in the context. Examples of chiral separation with HPLC and supercritical fluid chromatography are first demonstrated by using coated chiral stationary phases (CSPs). Optimum CD loading content on the coated CSPs was explored in the chiral separation of neutral analytes.

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Synthesis and Properties of 6A-Amino-6A-deoxy-α and β-cyclodextrin

Cited by 66 publications

References 0 publications

Reversal of Regioselectivity and Enhancement of Rates of Nitrile Oxide Cycloadditions through Transient Attachment of Dipolarophiles to Cyclodextrins

Reversal of Regioselectivity and Enhancement of Rates of Nitrile Oxide Cycloadditions through Transient Attachment of Dipolarophiles to Cyclodextrins

Pyrene-appended α-Cyclodextrin as a Fluorescent pH Probe Responding to a Wide Range

Monosubstituted positively charged cyclodextrins: Synthesis and applications in chiral separation

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