- Synthesis of immunostimulatory α- C -galactosylceramide glycolipids via sonogashira coupling, asymmetric epoxidation, and trichloroacetimidate- mediated epoxide opening
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Stereocontrolled syntheses of α-C-GalCer (2) and its α-C-acetylenic analogue 6 were accomplished in high efficiency by a convergent construction strategy from 1-hexadecene and d-galactose. The key transformations include Sonogashira coupling, Sharpless asymmetric epoxidation, and Et2AlCl-catalyzed cyclization of an epoxytrichloroacetimidate to generate protected dihydrooxazine 21.
- Liu, Zheng,Byun, Hoe-Sup,Bittman, Robert
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supporting information; experimental part
p. 2974 - 2977
(2010/11/16)
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- The influence of boric acid on the acetylation of aldoses: 'One-pot' syntheses of penta-O-acetyl-β-D-glucofuranose and its crystalline propanoyl analogue
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When glucose and boric acid are heated in acetic acid a soluble compound forms from which, with acetic anhydride and catalytic amounts of sulfuric acid, a mixture consisting of >90% of the glucofuranose per-acetates (α : β ratio 1 : 1.8) is obtained in high yield. In the absence of the sulfuric acid partial acetylation takes place and penta-O-acetyl-β-D-glucofuranose (α: β ratio 1 : 52) is obtainable in good yield by removal of boric acid and completion of the esterification by addition of acetic anhydride and pyridine. A new, crystalline glucofuranose, penta-O-propanoyl-β-D-glucofuranose, is obtained in 58% yield in a 'one-pot' procedure using boric acid. The effects of boric acid on the acid-catalysed acetylation of other aldo-hexoses and -pentoses suggest that the synthesis of furanosyl per-esters could be successful with xylose and idose as well as with glucose.
- Furneaux, Richard H.,Rendle, Phillip M.,Sims, Ian M.
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p. 2011 - 2014
(2007/10/03)
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- H-Beta zeolite as an efficient catalyst for per-O-acetylation of mono- and disaccharides
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Among the six different zeolites examined, H-beta is demonstrated to be a highly efficient and selective catalyst for the per-O-acetylation of various mono-and disaccharides and methyl glycosides.
- Bhaskar, Pallooru Muni,Loganathan, Duraikkannu
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p. 129 - 131
(2007/10/03)
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