Abstract
A versatile chemical conversion of adenosine to guanosine is described. Treatment of adenosine-1-oxide with cyanogen bromide afforded hydrobromide salt of 2-imino-6-β-D-ribofuranosyl-(1, 2, 4-oxadiazolo [2, 3-f] purine), which existed as N6-cyanoadenosine-1-oxide on neutralization. Methylation of the latter followed by treatment with alkali afforded N6-methoxy-2-aminoadenosine. The solvolysis of the product with liquid hydrogen sulfide gave 6-thioguanosine in high yield. Thioguanosine can be oxidatively hydrolyzed to guanosine by the known procedure. Catalytic hydrogenation of the oxadiazolopurine riboside in the presence of acetic acid gave 6-ureidopurine riboside.
