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Mahdi Faal Maleki - One of the best experts on this subject based on the ideXlab platform.
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nicotinium dichromate 3 carboxypyridinium dichromate ndc as an efficient reagent for the Oxidative Deamination of amines and aminophosphonates
Helvetica Chimica Acta, 2012Co-Authors: Sara Sobhani, Sima Aryanejad, Mahdi Faal MalekiAbstract:A new method for the efficient synthesis of aldehydes, ketones, and oxophosphonates from various types of amines (primary and secondary) and aminophosphonates via Oxidative Deamination by nicotinium dichromate (=3-carboxypyridinium dichromate; NDC) is described.
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Oxidative Deamination of α aminophosphonates and amines by zinc dichromate trihydrate zncr2o7 3h2o under solvent free conditions at room temperature
Synlett, 2010Co-Authors: Sara Sobhani, Mahdi Faal MalekiAbstract:A novel method for the rapid and efficient conversion of a variety ot α-aminophosphonates to α-ketophosphonates using ZnCr 2 O 7 ·3H 2 O via Oxidative Deamination under solvent-free conditions at room temperature is described. This method is also applicable to the rapid and highly selective oxidation of various types of ordinary amines (primary and secondary) to aldehydes and ketones in good to high yields.
Sara Sobhani - One of the best experts on this subject based on the ideXlab platform.
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nicotinium dichromate 3 carboxypyridinium dichromate ndc as an efficient reagent for the Oxidative Deamination of amines and aminophosphonates
Helvetica Chimica Acta, 2012Co-Authors: Sara Sobhani, Sima Aryanejad, Mahdi Faal MalekiAbstract:A new method for the efficient synthesis of aldehydes, ketones, and oxophosphonates from various types of amines (primary and secondary) and aminophosphonates via Oxidative Deamination by nicotinium dichromate (=3-carboxypyridinium dichromate; NDC) is described.
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Oxidative Deamination of α aminophosphonates and amines by zinc dichromate trihydrate zncr2o7 3h2o under solvent free conditions at room temperature
Synlett, 2010Co-Authors: Sara Sobhani, Mahdi Faal MalekiAbstract:A novel method for the rapid and efficient conversion of a variety ot α-aminophosphonates to α-ketophosphonates using ZnCr 2 O 7 ·3H 2 O via Oxidative Deamination under solvent-free conditions at room temperature is described. This method is also applicable to the rapid and highly selective oxidation of various types of ordinary amines (primary and secondary) to aldehydes and ketones in good to high yields.
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Oxidative Deamination of α-Aminophosphonates and Amines by Zinc Dichromate Trihydrate (ZnCr2O7˙3H2O) under Solvent-Free Conditions at Room Temperature
Synlett, 2010Co-Authors: Sara Sobhani, Faal MalekiAbstract:A novel method for the rapid and efficient conversion of a variety ot α-aminophosphonates to α-ketophosphonates using ZnCr 2 O 7 ·3H 2 O via Oxidative Deamination under solvent-free conditions at room temperature is described. This method is also applicable to the rapid and highly selective oxidation of various types of ordinary amines (primary and secondary) to aldehydes and ketones in good to high yields.
David Crich - One of the best experts on this subject based on the ideXlab platform.
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Use of hydroxylamines, hydroxamic acids, oximes and amines as nucleophiles in the Zbiral Oxidative Deamination of N-acetyl neuraminic acid. Isolation and characterization of novel mono- and disubstitution products
Carbohydrate Research, 2020Co-Authors: Mohammed Hawsawi, Michael G. Pirrone, Anura Wickramasinghe, David CrichAbstract:The Oxidative Deamination of N-nitroso N-acetylneuraminic acid (NeuAc) derivatives is a useful reaction for the formation of 5-desamino-5-hydroxy NeuAc derivatives and their stereoisomers. We demonstrated previously that replacement of the classical nucleophile in these reactions, acetic acid, by phenols resulted in a novel double displacement process with substitution of the acetoxy group at the 4-position taking place in addition to that of the 5-acetamido group, for which we postulated a mechanism centered on the formation of a highly reactive vinyl diazonium ion. We now extend these studies to encompass the use of hydroxylamine-based systems and weakly basic amines as nucleophile. We find that the nature of the product depends significantly on the pKa of the nucleophile, with the more acidic species typically affording only substitution at the 5-position, while the less acidic species give mixtures of elimination products and disubstitution products. The use of aniline as nucleophile is of particular note as it affords a novel aziridine spanning positions 4- and 5- of the neuraminic acid skeleton.
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stereoselective synthesis of 5 epi α sialosides related to the pseudaminic acid glycosides reassessment of the stereoselectivity of the 5 azido 5 deacetamidosialyl thioglycosides and use of triflate as nucleophile in the zbiral Deamination of sialic
Journal of Organic Chemistry, 2016Co-Authors: Bibek Dhakal, Szymon Buda, David CrichAbstract:With a view to the eventual synthesis of glycosyl donors for the stereocontrolled synthesis of pseudaminic acid glycosides, the stereocontrolled synthesis of a d-glycero-d-gulo sialic acid adamantanylthioglycoside carrying an axial azide at the 5-position is described. The synthesis employs levulinic acid as nucleophile in the Oxidative Deamination of an N-acetylneuraminic acid thioglycoside leading to the formation of a 3-deoxy-d-glycero-d-galacto-2-nonulosonic acid (KDN) derivative selectively protected as 5-O-levulinate. Replacement of the levulinate by triflate enables introduction of the axial azide and hence formation of the glycosyl donor. A shorter synthesis uses trifluoromethanesulfonate as nucleophile in the Oxidative Deamination step when the 5-O-triflyl KDN derivative is obtained directly. Glycosylation reactions conducted with the 5-azido-d-glycero-d-gulo-configured sialyl adamantanylthioglycoside at −78 °C are selective for the formation of the equatorial glycosides, suggesting that the synt...
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Oxidative Deamination of n acetyl neuraminic acid substituent effects and mechanism
Journal of the American Chemical Society, 2016Co-Authors: Szymon Buda, David CrichAbstract:A study of the mechanism of the Oxidative Deamination of the N-nitroso-N-acetyl sialyl glycosides leading with overall retention of configuration to the corresponding 2-keto-3-deoxy-d-glycero-d-galacto-nonulopyranosidonic acid (KDN) glycosides is described, making use of a series of differentially O-protected N-nitroso-N-acetyl sialyl glycosides and of isotopic labeling studies. No evidence is found for stereodirecting participation by ester groups at the 4- and 7-positions. Comparisons are drawn with Oxidative Deamination reactions of 4-amino-4-deoxy and 2-amino-2-deoxy hexopyranosides and a common mechanism is formulated involving the intermediacy of 1-oxabicyclo[3.1.0]hexyl oxonium ions following participation by the pyranoside ring oxygen. A minor reaction pathway has been uncovered by labeling studies in the β-thiosialosides that results in the exchange of the 4-O-acetyl group by the glacial acetic acid that serves as external nucleophile in the general Oxidative Deamination process. A mechanism is p...
Irwin J. Kopin - One of the best experts on this subject based on the ideXlab platform.
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a vesicular sequestration to Oxidative Deamination shift in myocardial sympathetic nerves in parkinson s disease
Journal of Neurochemistry, 2014Co-Authors: David S. Goldstein, Patricia Sullivan, Courtney Holmes, Gary W. Miller, Yehonatan Sharabi, Irwin J. KopinAbstract:In Parkinson disease (PD), profound putamen dopamine (DA) depletion reflects denervation and a shift from vesicular sequestration to Oxidative Deamination of cytoplasmic DA in residual terminals. PD also involves cardiac sympathetic denervation. Whether PD entails myocardial norepinephrine (NE) depletion and a sequestration-Deamination shift have been unknown. We measured apical myocardial tissue concentrations of NE, DA, and their neuronal metabolites 3,4-dihydroxyphenylglycol (DHPG), and 3,4-dihydroxyphenylacetic acid (DOPAC) from 23 PD patients and 23 controls and ascertained the extent of myocardial NE depletion in PD. We devised, validated in VMAT2-Lo mice, and applied 5 neurochemical indices of the sequestration-Deamination shift—concentration ratios of DOPAC:DA, DA:NE, DHPG:NE, DOPAC:NE, and DHPG:DOPAC—and used a kinetic model to estimate the extent of the vesicular storage defect. The PD group had decreased myocardial NE content (p<0.0001). The majority of patients (70%) had severe NE depletion (mean 2% of control), and in this subgroup all 5 indices of a sequestration-Deamination shift were increased compared to controls (p<0.001 for each). Vesicular storage in residual nerves was estimated to be decreased by 84-91% in this subgroup. We conclude that most PD patients have severe myocardial NE depletion, due to both sympathetic denervation and decreased vesicular storage in residual nerves.
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A vesicular sequestration to Oxidative Deamination shift in myocardial sympathetic nerves in Parkinson's disease.
Journal of Neurochemistry, 2014Co-Authors: David S. Goldstein, Patricia Sullivan, Courtney Holmes, Gary W. Miller, Yehonatan Sharabi, Irwin J. KopinAbstract:In Parkinson disease (PD), profound putamen dopamine (DA) depletion reflects denervation and a shift from vesicular sequestration to Oxidative Deamination of cytoplasmic DA in residual terminals. PD also involves cardiac sympathetic denervation. Whether PD entails myocardial norepinephrine (NE) depletion and a sequestration-Deamination shift have been unknown. We measured apical myocardial tissue concentrations of NE, DA, and their neuronal metabolites 3,4-dihydroxyphenylglycol (DHPG), and 3,4-dihydroxyphenylacetic acid (DOPAC) from 23 PD patients and 23 controls and ascertained the extent of myocardial NE depletion in PD. We devised, validated in VMAT2-Lo mice, and applied 5 neurochemical indices of the sequestration-Deamination shift—concentration ratios of DOPAC:DA, DA:NE, DHPG:NE, DOPAC:NE, and DHPG:DOPAC—and used a kinetic model to estimate the extent of the vesicular storage defect. The PD group had decreased myocardial NE content (p
Szymon Buda - One of the best experts on this subject based on the ideXlab platform.
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stereoselective synthesis of 5 epi α sialosides related to the pseudaminic acid glycosides reassessment of the stereoselectivity of the 5 azido 5 deacetamidosialyl thioglycosides and use of triflate as nucleophile in the zbiral Deamination of sialic
Journal of Organic Chemistry, 2016Co-Authors: Bibek Dhakal, Szymon Buda, David CrichAbstract:With a view to the eventual synthesis of glycosyl donors for the stereocontrolled synthesis of pseudaminic acid glycosides, the stereocontrolled synthesis of a d-glycero-d-gulo sialic acid adamantanylthioglycoside carrying an axial azide at the 5-position is described. The synthesis employs levulinic acid as nucleophile in the Oxidative Deamination of an N-acetylneuraminic acid thioglycoside leading to the formation of a 3-deoxy-d-glycero-d-galacto-2-nonulosonic acid (KDN) derivative selectively protected as 5-O-levulinate. Replacement of the levulinate by triflate enables introduction of the axial azide and hence formation of the glycosyl donor. A shorter synthesis uses trifluoromethanesulfonate as nucleophile in the Oxidative Deamination step when the 5-O-triflyl KDN derivative is obtained directly. Glycosylation reactions conducted with the 5-azido-d-glycero-d-gulo-configured sialyl adamantanylthioglycoside at −78 °C are selective for the formation of the equatorial glycosides, suggesting that the synt...
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Oxidative Deamination of n acetyl neuraminic acid substituent effects and mechanism
Journal of the American Chemical Society, 2016Co-Authors: Szymon Buda, David CrichAbstract:A study of the mechanism of the Oxidative Deamination of the N-nitroso-N-acetyl sialyl glycosides leading with overall retention of configuration to the corresponding 2-keto-3-deoxy-d-glycero-d-galacto-nonulopyranosidonic acid (KDN) glycosides is described, making use of a series of differentially O-protected N-nitroso-N-acetyl sialyl glycosides and of isotopic labeling studies. No evidence is found for stereodirecting participation by ester groups at the 4- and 7-positions. Comparisons are drawn with Oxidative Deamination reactions of 4-amino-4-deoxy and 2-amino-2-deoxy hexopyranosides and a common mechanism is formulated involving the intermediacy of 1-oxabicyclo[3.1.0]hexyl oxonium ions following participation by the pyranoside ring oxygen. A minor reaction pathway has been uncovered by labeling studies in the β-thiosialosides that results in the exchange of the 4-O-acetyl group by the glacial acetic acid that serves as external nucleophile in the general Oxidative Deamination process. A mechanism is p...
