Conversion of ω-terminal-acetylenic sugar derivatives into acetylenic glycosides and nucleosides, and formation of “double-headed nucleoside” analogs

Abstract

3,5-Di- O-acetyl-6,7-dideoxy-1,2- O-isopropylidene-β- L- ido- and α- d- gluco-hept-6-ynofuranose were separately deacetonated, and the products acetylated, to give the 1,2,3,5-tetra- O-acetyl analogs ( 2 and 6). Fusion of compounds 2 and 6 with 2,6-dichloropurine under acid catalysis produced 2,6-dichloro-9-(2,3,5-tri- O-acetyl-6,7-dideoxy-α- L- ido-hept-6-ynofuranosyl)-9 H-purine ( 3) and its β- d- gluco analog 7, respectively. Methanolic ammonia converted 3 in good yield into 2-chloro-9-(6,7-dideoxy-α- L- ido-hept-6-ynofuranosyl)-6-methoxy-9 H-purine. Treatment of compound 3 with mesityl nitrile oxide gave a “double-headed nucleoside” analog. Upon treatment with phenyl azide, the d- gluco derivative 7 produced another “double-headed nucleoside”. Fusion of 2 and 6 with p-nitrophenol yielded the respective p-nitrophenyl glycosides. The stereochemistry and regiospecificity of the reactions were verified spectroscopically.