70832-65-4Relevant academic research and scientific papers
An improved preparation of 2,3,5-tri-O-acyl-β-D-ribofuranosyl azides by the Lewis acid-catalysed reaction of β-D-ribofuranosyl acetates and trimethylsilyl azide: An example of concomitant formation of the α anomer by trimethylsilyl triflate catalysis
Stimac, Anton,Kobe, Joze
, p. 359 - 365 (1992)
An improved synthesis of 2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl azide (A) involves the reaction of trimethylsilyl azide in the presence of a Lewis acid with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose rather than the action of sodium azide upon t
Studies on the origin of stereoselectivity in the synthesis of 1,2-trans glycofuranosyl azides
Stimac, Anton,Kobe, Joze
, p. 149 - 160 (2007/10/03)
The stereoselectivity of the 1,2-trans directed, Lewis acid-catalysed azidation of peracylated furanoses was found to depend on the reactivity of the azide donor (azide nucleophilicity) and the configuration at the anomeric centre relative to the neighbouring 2-O-acyl group. Reactions of 1,2-trans glycosyl esters with highly nucleophilic azide donors, generated from SnCl4 and Me3SiN3, were stereospecific. The results are interpreted in terms of the rapid reaction of the azide species with bicyclic 1,2-acyloxonium (1,2-O-alkyliumdiyl-D-glycofuranose) ions, which were the primarily formed reactive intermediates. When using 1,2-cis glycosyl esters as starting materials the selectivity was reduced (90-94% de); the same is true with 1,2-trans counterparts if less nucleophilic Me3SiN3 in combination with Me3SiOTf catalyst was used. This occurred due to the appearance of the more reactive but less selective oxocarbenium (glycofuranoxonium) ions either as primarily formed reactive intermediates in the former case or after equilibration with acyloxonium ions in the latter case. Protected 1,2-trans β-D-glycofuranosyl azides with ribo, xylo and 3-deoxy-erythro-pento configurations were best prepared from the corresponding glycosyl esters using 0.05 equivalents of SnCl4, i.e., under anomerization-free conditions. Azidation of methyl glycofuranosides proceeds with inferior (80-90% de) and less predictable selectivity irrespective of the starting anomeric configuration. Copyright (C) 2000 Elsevier Science Ltd.
