- Conversion of 5-hydroxymethylfurfural into 6-(hydroxymethyl)pyridin-3-ol: A pathway for the formation of pyridin-3-ols in honey and model systems
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The formation of 6-(hydroxymethyl)pyridin-3-ol by ring expansion of 5-(hydroxymethyl)furfural (HMF) in the presence of ammonia-producing compounds was studied to determine the routes of formation of pyridin-3-ols in foods. 6-(Hydroxymethyl)pyridin-3-ol was produced from HMF in model systems, mostly at neutral pH values, as a function of reaction times and temperature and with an activation energy (Ea) of 74 ± 3 kJ/mol, which was higher than that of HMF disappearance (43 ± 4 kJ/mol). A reaction pathway is proposed, which is general for the formation of pyridin-3-ols from 2-oxofurans. Thus, it explains the conversions of furfural into pyridin-3-ol and of 2-acetylfuran into 2-methylpyridin-3-ol, which were also studied. When honey and sugarcane honey were heated, they produced different pyridin-3-ols, although 6-(hydroxymethyl)pyridin-3-ol was the pyridine-3-ol produced to the highest extent. Obtained results suggest that formation of pyridin-3-ols in foods is unavoidable when 2-oxofurans are submitted to thermal heating and ammonia (or ammonia-producing compounds) is present.
- Hidalgo, Francisco J.,Lavado-Tena, Cristina M.,Zamora, Rosario
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p. 5448 - 5454
(2020/06/08)
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- Convergent and selective synthesis of pyrrolidinones, piperidinones, dihydropyridinones and pyridinols from a common intermediate - Potential precursors of bioactive products
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Titanium-mediated cyclopropanation of natural and unnatural β-amino acid derivatives provides azabicyclo[3.1.0]hexan-1-ols as mixtures of diastereomers that are separable by silica-gel chromatography. Depending on the ring cleavage procedure employed, these compounds lead efficiently to diverse intermediates for the synthesis of pharmaceuticals. Thus, depending on the experimental conditions, basic treatment can furnish racemic pyrrolidinones as a mixture of diastereomers and piperidinones. In contrast, the synthesis of optically active dihydropyridinones was achieved through a one-pot FeCl 3/AcONa reaction or performed by using bis(sym-collidine)iodine hexafluorophosphate. Furthermore, whereas the palladium-mediated hydrogenolysis of these dihydropyridinones furnished both chiral piperidinones and original pyridinols, a CeIV-promoted radical process yielded chiral tricyclic piperidinones. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Jida, Mouhamad,Ollivier, Jean
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experimental part
p. 4041 - 4049
(2009/04/14)
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- A facile synthesis of 1,6-dideoxynojirimycin from l-sorbose
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A practical synthesis of 1,6-dideoxynojirimycin, a potent glycosidase inhibitor, starting from l-sorbose, is described.
- An, Jia-Ning,Meng, Xiang-Bao,Yao, Yun,Li, Zhong-Jun
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p. 2200 - 2203
(2007/10/03)
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- Negishi coupling strategy of a repetitive two-step method for oligoarene synthesis
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A novel repetitive two-step method for oligoarene synthesis, based on Negishi cross-coupling of zinciophenoxides or zinciopyridinoxides with aryl triflates and subsequent triflation of the hydroxy group, was developed. Reaction conditions were optimized for the preparation of the arylzinc compounds and the palladium-catalyzed cross-coupling step.
- Shimizu, Haruka,Manabe, Kei
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p. 5927 - 5931
(2007/10/03)
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- An efficient facile and selective hydroxylation of nitrogen heterocycles
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Nitrogen heterocycles have been efficiently hydroxylated under mild and neutral conditions by employing Cupric nitrate/phosphate buffer/30%hydrogen peroxide system. The present method afforded the biologically active and important hydroxy heterocycles. Th
- Nasreen, Aayesha,Adapa, Srinivas R.
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p. 501 - 506
(2007/10/03)
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- ELECTROCHEMICAL REDUCTION OF PRISTINAMYCIN IA AND RELATED STREPTOGRAMINS IN AQUEOUS ACIDIC MEDIUM
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The electrochemical reduction of the picolinoyl residue of pristinamycinIA and related streptogramins was performed at a mercury cathode, in aqueous medium.The presence of a peptidic lactone residue at the amide nitrogen atom markedly modified the expected cathodic behaviour of pyridyl carboxamides: in particular, we observed the reduction of the pyridyl ring into tetrahydropyridine derivatives.Thanks to a series of model heterocyclic carboxamides, increasing steric hindrance at the amide nitrogen position was shown to lead to enhanced reduction of the heterocyclic ring.
- Largeron, M.,Vuilhorgne, M.,Potier, I. Le,Auzeil, N.,Bacque, E.,and al.
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p. 6307 - 6332
(2007/10/02)
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- Substituted tetralins, chromans and related compounds in the treatment of asthma, arthritis and related diseases
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Substituted tetralins, chromans and related compounds which, by inhibiting 5-lipoxygenase enzyme and/or blocking leukotriene receptors, are useful in the prevention or treatment of asthma, arthritis, psoriasis, ulcers, myocardial infarction and related disease states in mammals, pharmaceutical compositions thereof, a method of treatment therewith, and to intermediates useful in the synthesis thereof.
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- The REDUCTION OF MANNICH BASES AND THEIR DERIVATIVES BY TRI-N-BUTYLTIN HYDRIDE
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Overall nuclear methylation of phenols was achieved by deamination of their Mannich bases and related derivatives with tri-n-butyltin hydride.The α-methylation of ketones was also similarly achieved.
- Chao, Herbert S.-I.
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p. 1207 - 1212
(2007/10/02)
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- On the Formation of 2-Acylpyrroles and 3-Pyridinols in the Maillard Reaction through Strecker Degradation
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The effects of pH, reactant ratio and reaction time on the yields of 5-methylpyrrole-2-carboxaldehyde (6), 6-methyl-3-pyridinol (7), methyl 2-pyrrolyl ketone (8) and 2-methyl-3-pyridinol (9) in the reaction of D-glucose with glycine at 100 deg C in aqueous solution have been studied.THe use of -D-glucose showed that the methyl group in each of 6-9 is derived from C-6 of the glucose.The formation of 6-9 from some potential intermediates in the glucose-glycine reaction has also been investigated.The results support the previously proposed routes to 6 and 7 but disqualify those to 8 and 9.Based on the smooth formation of 8 and 9 from 2-deoxy-D-arabino-hexose (12) and ammonia, a new route to 8 and 9, through an enamine derivated from 12, is proposed.This route involves a modified Strecker degradation, which was supported by the formation of 2,3-dideoxy-D-erythro-hexose from 3-deoxy-D-ribo-hexose and glycine.
- Nyhammar, Tomas,Olsson, Kjell,Pernemalm, Per-Ake
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p. 879 - 890
(2007/10/02)
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