Nucleosides with acyl azides

Acyl azides show selectivity for acylation at secondary (rather than primary) hydroxyl groups in nucleosides. Thus, on reaction with an excess of N-(benzyIoxycarbonyl)glycyIglycyl azide in 1,4-dioxane-water at 8° and pH 9, adenosine gave the 2 (3 )-0-(aminoacyl) and 2, 3 -di-0-(aminoacyl) derivatives.183 Furthermore, adenosine and uridine were converted into a variety of 2 (3 )-esters of aromatic amino acids by reaction with the appropriate acyl azide.184... 

In contrast to various syntheses of 1,2,3-triazole nucleosides by cycloaddition of glycosyl azides to substituted alkynes (see Section 4.11.5.2.2 and e.g. (7ojhci269)), the acid-catalyzed fusion of methyl l,2,3-triazole-4-carboxylate, 4-cyano-l,2,3-triazole and 4-nitro-l,2,3-triazole (156) with an acylated ribofuranose provides the corresponding 4-substituted 2/3-D-ribofuranosyl-l,2,3-triazoles (157) along with the l-/3-D-isomers (158) (72jhcii9s). 

Several papers describe the synthesis of azido-sugar precursors to amino-sugar nucleosides. The unsaturated nucleosides (34) were converted to the corresponding amino-compounds (35) by sequential treatment with triphenyl-phosphine-tetrabromomethane and lithium azide followed by reduction, the product amines then being coupled to amino-acids to give amino-acyl derivatives, which showed slight antitumour activity. " A facile new synthesis of 2 -amino-2 -... 

Cytidine has been converted into l-(5-amino-5-deoxy-j8-D-arabinofuranosyl) cytosine by a sequence of reactions involving A-benzoylation, sulphonation, acetylation, displacement with azide ion, e/c., and l-(3-amino-3-deoxy-jS-D-arabinofuranosyl)-6-azauracil was derived from 2, 3 -di-0-methanesulphonyl-5 -O-trityl-6-azauridine via 2,2 - and 2, 3 -anhydro-nucleosides. Other syntheses have been accomplished by the condensation of an appropriately derivatized amino-sugar with either a pyrimidine or purine derivative for example, the Hilbert route was used to prepare l-(2-amino-2-deoxy-a-D-arabino- and -jS-o-xylo-furanosyl)cytosine. > The reactivity of l,3,4,6-tetra-0-acetyl-2-acyl-amido-2-deoxy-j3-D-glucopyranoses in condensation reactions with 2,6-dichloro-purine, theophylline, and 6-benzylaminopurine was shown to be in the order benzamido > acetamido > phthalimido. 9-(3-Acetamido-2,5-di-0-acetyl-3-deoxy-j8-D-ribofuranosyl)-2,6-dichloropurine has been synthesized and converted into the corresponding 2,6-diamino- and 6-amino-2-chloro(fluoro)-nucleosides. ... 

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