3) The reductocondensation of D-glucose (VIII) and butylamine by means of H2 over Pd/C in ethanol gives N-butylglucamine (IX), which is submitted to a biochemical oxidation by means of Gluconobacter oxidans in water to yield 6-(butylamino)-6-deoxy-a-L-sorbofuranose (X). Finally, this compound is submitted to a reductive cyclization with H2 over Pd/C in ethanol/water. 4) The selective hydrolysis of 1,2:4,6-di-O-isopropylidene-a-L-sorbofuranose (XI) (together with some of its 1,3:4,6-isomer) by means of H2SO4 in methanol gives 1,2-O-isopropylidene-a-L-sorbofuranose (XII), which is treated with tosyl chloride, triethylamine and pyridine to yield the monotosylated sugar (XIII). Reaction of the protected sugar (XIII) with butylamine in hot pyridine/triethylamine affords 6-(butylamino)-6-deoxy-1,2-O-isopropylidene-a-L-sorbofuranose (XIV), which is finally submitted to a reductive cyclization by means of H2 over Pd/C in water. 5) Directly by reductocondensation of 1-deoxynojiri-mycin (XV) with butyraldehyde (XVI) by means of H2 over Pd/C in methanol or with NaBH3CN in methanol/ HCl.
1) The reductive ring opening of 2,3,4,6-tetra-O-benzyl-a-D-glucopyranose (I) with LiAlH4 in THF gives the diol (II), which is oxidized by means of DMSO, trifluoroacetic anhydride and triethylamine in dichloromethane to yield the unstable ketoaldehyde (III), which, without isolation, is submitted to a reductocyclization with butyl-amine and NaBH3CN in methanol to afford the protected iminosugar (IV). Finally, this compound is debenzylated by means of Li and NH3 in THF. 2) The oxidation of 1,2-O-isopropylidene-5-oxo-a-D-glucofuranose (V) by means of Bu2SnO and Br2 in refluxing methanol provides the 5-oxoglucofuranose derivative (VI), which is hydrolyzed with Dowex 50W-X8 in water to yield 5-oxo-D-glucose (VII). Finally, this compound is submitted to a reductocyclization with butyl-amine and NaBH3CN in methanol.