Syntheses of 3',4',5,6-tetradioxyneamine and 5,6-dideoxyneamine

3',4',5,6-Tetradoxyneamine (7) was synthesized from neamine by the reaction sequence N-acetylation, O-mesylation, treatment with sodium iodide-zinc dust, hydrogenation, and base hyrolysis, Alternatively, 7 was obtained by treatment of tetra-(N-methoxycarbonyl)neamine with sulphuryl chloride, followed by hydrogenation in the presence of palladium-on-charcoal and triethylamine, and removal of the N-protecting groups. 5,6-Dideoxyneamine (11) was synthesized from known 5,6-O-cyclohexylidene-tetra-(N-methoxycarbonyl)neamine by the reaction sequence 3',4'-O-acetylation, removal of the 5,6-O-cyclohexylidene group, 5,6-di-O-mesylation, treatment with sodium iodide-zinc dust, hydrogenation, and base hydrolysis. An alternative route involved treatment of 3',4'-di-O-acetyl-tetra-(N-methoxycarbonyl)-neamine (8) with sulphuryl chloride, hydrogenation of the product, and removal of the protecting groups to give 11.