d-ribofuranosyl azides. A direct conversion of 1-O-acyl-2,3-O-isopropylidene-d-ribofuranose into d-ribofuranosyl azides
Reactions of azidotrimethylsilane with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-ribofuranose (2), and the 1,5-di-O-p-nitrobenzoyl and 1,5-di-O-acetyl derivatives, 4 and 5 respectively, of 2,3-O-isopropylidene-β-d-ribofuranose, in the presence of the Lewis acids aluminum chloride, titanium tetrachloride, or boron trifluoride etherate were studied. All three Lewis acids readily catalyze the quantitative conversion of 2 into its β-d-ribofuranosyl azide, whereas only aluminum chloride is a suitable catalyst for conversion of 4 and 5 into their azides; boron trifluoride etherate is ineffective, and titanium tetrachloride causes partial decomposition. Contrary to the behavior of 2, which gives only the β azide, 4 and 5 give, in excellent yield, anomeric mixtures of azides in which the β azide preponderates. Although dichloromethane and acetonitrile are appropriate solvents for the reaction of 2, only acetonitrile is suitable for 4 and 5, as use of the former results in the co-production of related d-ribofuranosyl chlorides. © 1983.
d-ribofuranosyl azides. A direct conversion of 1-O-acyl-2,3-O-isopropylidene-d-ribofuranose into d-ribofuranosyl azides.
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