Idopyranose

When heated to 100 CC/ D-idose undergoes a reversible loss of water and exists primarily as 1,6-anhydro-n-idopyranose. 

Carba-y5-DL-idopyranose (77) was prepared from (readily accessible) (l,2,4/3)-5-(hydroxymethyl)-5-cyclohexene-l,2,3,4-tetrol (75) by hydrogenation over a platinum catalyst, acetylation of the product, and 0-deacetylation. 

Similarly, 180 was transformed into 5a-carba-a-D-glucopyranose penta-acetate (98) and 5a-carba- 8-L-idopyranose pentaacetate (183). 

CjoH NOuP CH3OH 1, 2,3,4-Tetra-0-acetyl-5,6-dideoxy-6-C-nitro-5-C-(phenylphosphinyl)-/ -L-idopyranose, methanolate (IDPYRS)105... 

Dermatan sulfate, also termed chondroitin sulfate B, a related glycosaminoglycan constituent of connective tissue, was known to be composed of galactosamine and a uronic acid, originally believed to be glucuronic acid but then claimed to be iduronic acid based largely on color reactions and paper chromatography. However, the d or L-enantiomer status of the latter monosaccharide was not clear. Jeanloz and Stoffyn unequivocally characterized the monosaccharide as L-iduronic acid by consecutive desulfation, reduction, and hydrolysis of the polysaccharide, followed by isolation of the crystalline 2,3,4-tri-0-acetyl-l,6-anhydro-/ -L-idopyranose, which was shown to be identical to an authentic specimen synthesized from 1,2-0-isopropylidene-/ -L-idofuranose.34... 

Notiz iiber l,6-Anhydro-2-S-benzyl-2-thio-/3-l>idopyranose, by L. Vegh and E. Hardegger, Helv. Chim. Acta, 56 (1973) 1961-1962. 

Entsprechende Gleichgewichte stellen sich immer ein, wenn Glyko-side, Oligo- und Polysaccharide einer sauren Hydrolyse unterworfen werden, und auch bei der Einwirkung von wafirigen Sauren auf Aldo-hexosen (sog. Reversion i87,i92,243,253)) Nach der sauren Hydrolyse und Reduktion des P-Heparins wurde aus der dort anwesenden L-Iduron-saure 1,6-Anhydro-p-L-idopyranose (als 2,3,4-Tri-O-acetat) erhalten h... 

Problem 22.32 Draw the more and less stable conformations of a) /3-o-mannopyranose (Problem 22.11), (f>) a-D-idopyranose (idose is the C epimer of gulose see Problem 22.27), (c) /3-L-glucopyranose (/3-l- and /3-Dare enantiomers). Explain each choice. ... 

The equilibrium compositions of aqueous solutions of some aldoheptoses are listed in Table III. Because the additional carbon atom in the side chain does not introduce additional steric interactions, the composition of solutions of heptoses is similar to that of the homomorphous hexoses, with only one exception, namely, n-glycero-n-ido-heptose, 92 a-D-Idopyranose in solution is a mixture of the 4Ci and 1C4 conformant) S. J. Angyal and R. J. Beveridge, Carbohydr. Res., 65 (1978) 229-234. 

Much information concerning such a ring enlargement has been accumulated. For historical reasons, the preparation of L-idopyranose derivatives will be discussed first. 

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