Wanderung von Acyl bei den Glyceriden

Fischer, Emil

doi:10.1002/cber.19200530904

Cited by 116 publications

(48 citation statements)

References 4 publications

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“…[20] The consecutive AcM is strongly pH dependant and small pH changes lead to pronounced differences in concentrations of the intermittently generated mono-O-acetyl D-glucoses (1). [28] A transformation at pH 7. in situ 1D selTOCSY as well as 2D COSY, TOCSY, and NOESY spectra can be recorded, when intermediates are accumulated in higher concentrations.…”

Section: Resultsmentioning

confidence: 99%

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In situ proton NMR study of acetyl and formyl group migration in mono‐O‐acyl D‐glucose

Brecker

Mahut

Schwarz

et al. 2009

Magnetic Reson in Chemistry

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Acetyl and formyl group migration, mutarotation, and hydrolysis of mono-O-acylated glucose are studied by in situ 1D and 2D (1)H NMR spectroscopy. Alpha-D-glucosyl-1-acetate and alpha-D-glucosyl-1-formate serve as sole starting materials. They are generated in situ by configuration retaining glucosyltransfer from alpha-D-glucosyl-1-phosphate to formate and acetate, which is catalyzed by the Glu-237 --> Gln mutant of Leuconostoc mesenteroides sucrose phosphorylase. Temporary accumulated regio-isomeric mono-O-acyl D-glucoses are identified, characterized, and quantified directly from the reaction mixture. Time courses of the transformations give insight into pH dependence of acyl group migration and mutarotation as well as into the stability of various regioisomers.

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Section: Resultsmentioning

confidence: 99%

“…Migration of small acyl groups in partially O-acylated carbohydrates or polyhydroxy compounds is well known since the 1920s [1,2] and has occasionally been used in synthetic strategies. [3] However, it makes the O-acetyl group an unusual protecting group when selective protection of a secondary hydroxyl group in a saccharide is required.…”

Section: Introductionmentioning

confidence: 99%

In situ proton NMR study of acetyl and formyl group migration in mono‐O‐acyl D‐glucose

Brecker

Mahut

Schwarz

et al. 2009

Magnetic Reson in Chemistry

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“…This situation also confounded a study of solidstate acyl shift of glycerol 1,2-dipalmitate to the 1,3 isomer (Dorset and Pangborn, 1979) from which the available data also seemed to support an incorrect molecular conformation. Subsequent determination of its x-ray crystal structure (Pangborn and Dorset, 19831, which was identical to its dilauroyl homolog, finally revealed that early assumptions of an intramolecular acyl shift mechanism (Fischer, 1920) to be unfounded.…”

Section: High Molecular Weight Compounds In Small Unit Cellsmentioning

confidence: 99%

Electron crystal structure analysis of small organic molecules

Dorset

1985

J. Elec. Microsc. Tech.

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Electron crystallography of small organic molecules, i.e., electron diffraction crystal structure analysis, has been long recognized to possess definite advantages over neutron and x-ray diffraction techniques for the investigation of microcrystalline preparations. Quantitative application of the technique to real structural problems, on the other hand, had been hindered initially by an inadequate theoretical model. Yet, as demonstrated in this review of the methodology, the adequate recognition of limiting factors due to n-beam dynamical scattering and crystal deformation permits design of optimal diffraction experiments which yield intensity data suitable for ab initio structure analysis. Representative crystallographic analyses discussed here underscore the utility of this technique as a probe of organic molecular structure at atomic resolution.

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“…In acyl migration, the aglycone is transferred from the 1b position to the neighboring 2-hydroxyl group on the glucuronic acid moiety via an ortho-acid ester intermediate. 1,2) This process continues on to the OH-groups at C-3 and C-4, thereby forming several regioisomers. The glucuronide regioisomers readily ring-open and mutarotate to give a-and b-anomers.…”

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Kinetics of Intramolecular Acyl Migration of 1.BETA.-O-Acyl Glucuronides of (R)- and (S)-2-Phenylpropionic Acids.

Hasegawa

Akira

Shinohara

et al. 2001

Biological & Pharmaceutical Bulletin

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The conjugation of xenobiotic carboxylic acids with b-Dglucuronic acid to yield 1-O-acyl-b-D-glucopyranuronates (1b-O-acyl glucuronides) is a major metabolic pathway for many compounds, including 2-arylpropionic acids (profens). The 1b-O-acyl glucuronides are labile and reactive in neutral and mildly alkaline aqueous solution, and undergo both hydrolysis and intramolecular acyl migration (Fig. 1). In acyl migration, the aglycone is transferred from the 1b position to the neighboring 2-hydroxyl group on the glucuronic acid moiety via an ortho-acid ester intermediate. 1,2) This process continues on to the OH-groups at C-3 and C-4, thereby forming several regioisomers. The glucuronide regioisomers readily ring-open and mutarotate to give a-and b-anomers. The acyl migrations are generally reversible, but acyl migration from C-2 to C-1 to reform the 1b-O-acyl glucuronide is not commonly observed. These acyl glucuronides are capable of reacting with protein nucleophiles to form covalent adducts.3-12) The protein adducts have been hypothesized as mediators of hypersensitive responses to carboxylate drugs. 1,13) Profens possess a chiral center and are marketed as racemates. Profens are metabolized predominantly to the diastereomeric acyl glucuronides with different physicochemical properties. Consequently, the diastereomeric acyl glucuronides might have distinct toxicological actions and be differentially eliminated. Although the stability of the diastereomeric acyl glucuronides has been investigated in several profens, 7,[14][15][16][17][18][19] little information is currently available on the factors that contribute to stereoselective differences in the degradation process.Enantiomeric 2-phenylpropionic acids (PAs) possess the fundamental structure of profens (Chart 1) and have been used as model substrates of profens to study the stereoselective metabolism and disposition of profens. PAs show similar pharmacokinetic properties to other profens, as observed in stereoselective isomerization and glucuronidation in rodents. The stereoselective acyl migration of diastereomeric 1b b-O-acyl glucuronides of (R)-and (S)-2-phenylpropionic acid [(R)-1PG and (S)-1PG, respectively] in phosphate buffer (pH 7.4) at 310 K was investigated using HPLC. The disappearance of (R)-1PG was faster than that of (S)-1PG according to pseudo first-order kinetics. A kinetic model describing the degradation reactions was constructed. The rate constant for acyl migration from the 1b b-O-isomer to the 2-O-acyl isomer (k 12 ) was about one order magnitude larger than that for hydrolysis from 1b b-O-acyl isomer to aglycone (k 10 ). The k 12 of (R)-1PG (0.377؎0.005 h ؊1 ) was about two times larger than that of (S)-1PG (0.184؎0.003 h ؊1 ). The results indicated that the stereoselectivity in the degradation of 1PG was apparently governed by the acyl migration from 1-isomer to 2-isomer. The kinetic parameters for acyl migration from 1-isomer to 2-isomer were estimated from temperature-dependent experiments using the transition state theory. The value o...

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Wanderung von Acyl bei den Glyceriden

Cited by 116 publications

References 4 publications

In situ proton NMR study of acetyl and formyl group migration in mono‐O‐acyl D‐glucose

In situ proton NMR study of acetyl and formyl group migration in mono‐O‐acyl D‐glucose

Electron crystal structure analysis of small organic molecules

Kinetics of Intramolecular Acyl Migration of 1.BETA.-O-Acyl Glucuronides of (R)- and (S)-2-Phenylpropionic Acids.

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