Idopyranose pentaacetate

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

Furthermore, one of the hitherto unknown two pseudo-sugars, pseudo-P-DL-ido-pyranose (77) was synthesized from readily accessible (l,2,4/3)-5-(hydroxymethyl)-5-cyclohexene-l,2,3,4-tetrol (75) [24], Catalytic hydrogenation of 75 in the presence of platinum catalyst gave pseudo-p-DL-idopyranose pentaacetate (76) after acetylation. 

The 220-MHz, p.m.r. spectrum of a-D-idopyranose pentaacetate (in acetone-dg) is also first-order, in contrast to its 100-MHz spectrum, which shows strong distortions of the intensities of the lines in the H-2 and H-3 multiplets.60 Methine-proton signals that overlap at 100 MHz are separated in the 220-MHz spectra of ZV-acetyl-a-D-glucofuranosylamine (4), its /J-D-galacto isomer61 (5), and 3,4,5,6-... 

In an extension to aldohexose peracetates, the favored form of a-D-idopyranose pentaacetate in solution in acetone or chloroform was found to be the CJ(d) conformer, having four substituents axially and one equatorially attached. a-D-Altropyranose pentaacetate had previously been reported also to adopt the CJ(d) conformation, having three substituents axial and two equatorial. Consideration of the observed proton spin-couplings allowed the exclusion of the boat or skew forms as major contributors to the conformational populations for both compounds near room temperature. 

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