Glucopyranose pentaacetate carba

When 35 was heated in acetic acid containing hydrogen bromide, the tribromide 46 was obtained as a single product in 74% yield. Debromina-tion of 46 with zinc dust in acetic acid furnished the cyclohexene derivative 47, which was converted into compound 48 by osmium tetraoxide hydroxyl-ation and acetylation. The substitution reaction of 48 with acetate ions provided carba-a-DL-glucopyranose pentaacetate (49), which gave the carba-sugar 50 on hydrolysis. ... 

Analogously, for preparation of racemic carba-a-glucopyranose 49 from 52, esterification of (—)-52 furnished the ester 95, which was transformed into compound 96 by debromination with zinc dust and acetic acid. Stereoselective hydroxylation of 96 with osmium tetraoxide and hydrogen peroxide, followed by acetylation, gave compound 97. Lithium aluminum hydride reduction of 97, and acetylation of the product, gave pentaacetate 98, which was converted into 99 by hydrolysis. ... 

Debenzylation of 122 and 123, followed by acetylation, afforded the pentaacetates 98 and 124, which were respectively converted into carba-a-D-glucopyranose (99) and carba-/ -L-altropyranose (125) on hydrolysis. ... 

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

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