Topic
Pyranose
About: Pyranose is a research topic. Over the lifetime, 1619 publications have been published within this topic receiving 35348 citations. The topic is also known as: pyranoses & hexopyranose.
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TL;DR: Application of an iron-mediated hydrogen atom transfer/Michael-Giese coupling enables the anomeric quaternization of readily available exo-glycals with good to complete stereocontrol in the pyranose and furanose series.
23 citations
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TL;DR: The quinone-dependent pyranose dehydrogenase (PDH) purified from culture media of the basidiomycete fungus Agaricus xanthoderma catalyzed the simultaneous oxidation of lactose to β- d -galactopyranosyl-(1 → 4)- d- arabino -hexos-2-ulose (2-dehydrolactose) and lactobiono-1,5-lactone, with the latter spontaneously hydrolyzing to lactobionic acid as discussed by the authors.
Abstract: The quinone-dependent pyranose dehydrogenase (PDH) purified from culture media of the basidiomycete fungus Agaricus xanthoderma catalyzed the simultaneous oxidation of lactose to β- d -galactopyranosyl-(1 → 4)- d- arabino -hexos-2-ulose (2-dehydrolactose) and lactobiono-1,5-lactone, with the latter spontaneously hydrolyzing to lactobionic acid. These products were identified by MS and in situ NMR spectroscopy. C-2 oxidation at the reducing moiety of lactose was confirmed by analysis of N,N -diphenylhydrazone derivatives of the reaction products. The proportions of C-1 to C-2 oxidation varied according to the source of PDH, ranging from almost exclusive formation of lactobionic acid to 2-dehydrolactose as a major product. The highest selectivity for C-2 was exhibited by PDH from A. xanthoderma and A. meleagris . Yields of 2-dehydrolactose in laboratory transformations monitored by HPLC approached 75%. This dicarbonyl derivative may serve as a key intermediate in a potential process for adding value to lactose by its (chemo)enzymatic isomerization to lactulose. A minor product in the PDH–lactose reaction mixtures formed on prolonged incubations with excess of oxidant was identified through its hydrazone derivative as β- d -galactopyranosyl-(1 → 4)- d- threo -hexos-2,3-diulose (2,3-didehydrolactose).
23 citations
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TL;DR: In this paper, the primary alkoxyl radical generated by reaction of 1-(2-hydroxyethyl)-glycosides with DIB and iodine can undergo regioselective intramolecular hydrogen abstraction (IHA) reactions to furnish four different dioxabicyclic systems derived from carbohydrates.
23 citations
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TL;DR: In this article, cyclic ketones were obtained when C2 hydroxymethylated carbohydrates undergo a tandem β-fragmentation-cyclization reaction promoted by the system iodosylbenzene-iodine, under mild conditions.
23 citations
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TL;DR: The practical synthesis of orthogonally protected five-, six-, and seven-membered carbohydrate derivatives allows the rapid preparation of analogues aimed at discovering the role of ring size and individual hydroxyl moieties on the pyranose skeleton.
Abstract: Numerous biologically active natural products contain furanoses and pyranoses with mono- and dihydroxylated substituents. However, much of the structure−activity studies on such molecules is gathered on the aglycons without attention to the corresponding carbohydrate components. Consequently, there are few synthetic procedures that enable the rapid preparation of mono- and dihydroxyfuranoses and mono- and dihydroxypyranoses and no report for a 3,4-dihydroxyoxepanose. In this article we report the practical synthesis of orthogonally protected five-, six-, and seven-membered carbohydrate derivatives. The succinct manner in which these molecules were synthesized allows the rapid preparation of analogues aimed at discovering the role of ring size and individual hydroxyl moieties on the pyranose skeleton.
23 citations