Interactions of spin-labeled substrates with chymotrypsin and with cycloamyloses

Flohr, Kathleen; Paton, R. M.; Kaiser, E. T.

doi:10.1021/ja00838a041

Cited by 70 publications

(26 citation statements)

References 7 publications

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“…Only one chiral oxoammonium salt, 7, has been prepared from the (+)-enantiomer of the corresponding nitroxide, 91 and it showed no enantioselectivity in a number of oxidations. 85,92 Given the large number of known chiral nitroxides, 27,90,93 -101 few have been investigated as oxidation catalysts.…”

Section: Two-electron Secondarymentioning

confidence: 99%

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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The discovery in 1959 of stable nitroxide‐based free radicals such as the prototypical 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) led to their use as electron spin resonance (ESR) spin labels in chemistry, biomedicine, and materials science. These nitroxides are prepared by the oxidation of secondary amines that contain no hydrogen atoms on the alpha‐carbons. The unique redox properties of nitroxides enable their use as oxidants in organic synthesis. The varied preparation and uses of oxoammonium salts as stoichiometric oxidants for alcohols are one subject of this review. Oxoammonium ions as oxidants for alcohols have a number of advantages, for example, the method is heavy‐metal free and some of the reactions can be performed in water or aqueous mixtures. A few side reactions are associated with these oxidations. The most serious is the fast reaction of the oxoammonium ion with free amines The several ways these oxidation reactions can be carried out are discussed in detail. They are: Oxidations using stoichimetric quantities of preformed oxoammonium salts carried out in either acidic, neutral, or basic conditions; reactions in which stoichiometric quantities of oxoammonium salts are generated in situ by disproportionation of a nitroxide in the presence of a strong acid; nitroxide‐catalyzed oxidations using a secondary oxidant; efficient nitroxide‐catalyzed oxidations of primary alcohols to carboxylic acids; and oxidations of primary alcohols or hemiacetals that can lead to lactones.

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Section: Two-electron Secondarymentioning

confidence: 99%

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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“…17 The ESR detection of the formation of cyclodextrin (CD) inclusion complexes with nitroxide radicals by Kaiser et al in 1970 18 gave rise to extensive work on the stereochemical investigation of CD complexes by ESR. Enantioselective complexation of cyclohexa-and cycloheptaamylose with nitroxide esters and subsequent stereoselective catalytic hydrolysis of the esters was detected and investigated by means of ESR spectroscopy by Kaiser et al in 1975. 19 However, no significant differences (only different intensities of the peaks) were found between the ESR spectra of the diastereomeric complexes.…”

mentioning

confidence: 99%

“…Enantioselective complexation of cyclohexa-and cycloheptaamylose with nitroxide esters and subsequent stereoselective catalytic hydrolysis of the esters was detected and investigated by means of ESR spectroscopy by Kaiser et al in 1975. 19 However, no significant differences (only different intensities of the peaks) were found between the ESR spectra of the diastereomeric complexes. Rassat et al reported the same distinguishing features of the diastereomeric complexes of b-cyclodextrin with a nitroxide biradical in 1979.…”

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confidence: 99%

Solid‐state ESR differentiation between racemate versus enantiomer

et al. 2006

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“…proposed as P-CD has been applied to numerous Upon addition of a molar equivalent of P-CD to reactions related to hydrolysis and decarboxyla-the solution, the triplet signal of intensity ratio 1: 1: 1 tlon. Electron spin resonance (esr) SPectrosCoPY 1s lost symmetry with a marked broadening (with one of those methods, but examples are few (1)(2)(3)(4). decrease of the ratio of peak height to width) of the Keiser and CO-workers (1-3) used nitroxyl radicals highest field peak = -1) (see Fig.…”

mentioning

confidence: 99%

“…2c). Competitive inclusion between 1 and TCAA according to reactions [I] and [3], respectively, is apparent.…”

mentioning

confidence: 99%

Competitive inclusion of chloro-substituted acetic acids into β-cyclodextrin monitored by rotational correlation frequencies of 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy radical

Motozato¹,

Nishihara²,

Hirayama³

et al. 1982

Can. J. Chem.

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1959 (1982).Competitive inclusion in P-cyclodextrin between 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy and chloro-substituted acetic acids has been monitored by esr spectroscopy. The temperature dependence of the rotational correlation frequencies calculated by Kivelson's equation, using esr spectra of the radical, suggests that a structural change of P-cyclodextrin occurs at about 30°C and that trichloroacetic acid is included extensively at 20-3S°C, but significant inclusion of acetic acid is not observed. The degree of competitive inclusion is in the order of trichloro, dichloro, and rnonochloroacetic acids over the range of 20-80°C. Carbon-13 nmr studies also prove the inclusion of trichloroacetic acid showing an inclusion shift of the trichloromethyl carbon by 1.4 ppm.

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Interactions of spin-labeled substrates with chymotrypsin and with cycloamyloses

Cited by 70 publications

References 7 publications

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

Solid‐state ESR differentiation between racemate versus enantiomer

Competitive inclusion of chloro-substituted acetic acids into β-cyclodextrin monitored by rotational correlation frequencies of 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy radical

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