5-Deoxy-5- -£-idopyranoses

When either of the two methods in the previous Subsection is employed in order to introduce a phosphino (or phosphinyl) group at C-5 of 5-deoxy-D-xyZo-hexofuranoses, only 5-deoxy-5-phosphino- (or -5-phos-phinyl)- L-idopyranoses are produced for instance, 50 — 60 (and 64) — 63 (and 65), and 73 — 78 — 85 — 88 — 90. Therefore, in order to prepare hexopyranoses of the D-gluco type having phosphorus in the hemiacetal ring, an alternative approach had to be devised. 

Fic. 1.—ORTEP68 Representation53 of a Molecule of l,2,3,4-Tetra-0-acetyl-5,6-di-deoxy-5-C-[(5J-phenylphosphinylj-/ -L-idopyranose (93). 

Another route to 5-amino-5-deoxy-L-idose proceeds from 5-(benzyl-amino)-5-deoxy-l,2-0-isopropylidene-R-L-idurononitrile (56), which is readily obtainable from 1,2-O-isopropylidene-a-D-xj/lo-pentodialdo-1,4-furanose (13) by reaction with benzylamine and hydrogen cy-anide. Partial hydrogenation of the nitrile 56 by the Kuhn procedure, in acid solution, leads to the hexodialdose (57), which is reduced with sodium borohydride to 5-amino-5-deoxy-l,2-0-isopro-pylidene-jS-L-idofuranose. From this compound, tbe acyclic bisulfite adduct (58) is obtained by reaction with sulfiirous acid. Treatment of 58 with barium hydroxide gives crystalline 5-amino-l,6-anhydro-5-deoxy-jS-L-idopyranose (60) in almost quantitative yield. The equilibrium between the pyranose form (61) and its 1,6-anhydride (60) lies far on the side of Ae bicyclic form (60). The equilibrium can be evaluated from the optical rotation of the solution obtained by treat-... 

In the aldohexose series, 5-(benzylamino)-l,2-0-cyclohexylidene-5-deoxy-L-idurononitrile gives, on acid hydrolysis, an almost quantitative yield of N-benzyl-2-cyano-5-hydroxypyridinium chloride. On partial, catalytic hydrogenation of this aminonitrile, 5-(benzylamino)-I,2-0-cyclohexylidene-5-deoxy-L- do-hexodialdo-l,4-furanose is obtained. This compound is reducible with sodium borohydride to crystalline 5-(benzylamino)-l,2-0-cyclohexylidene-5-deoxy-L-idofur-anose which, on removal of the cyclohexylidene group with acid, forms the intermediate 5-(benzylamino)-5-deoxy-L-idopyranose this then loses three molecules of water per molecule, to give N-benzyl-5-hydroxy-2-(hydroxymethyl)pyridinium chloride. It is therefore clear that the transformation of 5-aminoaldoses into pyridine derivatives in acid solution is not prevented by the monoalkylation of the amino group. 

In 2,3,4-tri-0-acetyl-l,6-anhydro-)8-D-idopyranose, the most intensive ions are formed by cleavage of the ring between C-1 and C-2 (primary degradation C). In the spectrum of 6-acetamido-2,3,4-tri-0-acetyl-I,6-anhydro-6-deoxy-/3-L-idopyranose, the bicyclic fragments of mass number 168 and 126 are the most intensive ions. They are formed without cleavage of the ring, according to Scheme 2 (primary... 

Hanaya, T, Fujii, Y, Ikejiri, S, Yamamoto, H, A new route for preparation of 5-deoxy-5-hydroxyphosphinyl-D-gluco- and L-idopyranose derivatives. Heterocycles, 50, 323-332, 1999. 

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