Anhydro sugars 3- deoxy sugars from

Deoxy-D-jcylo hexose 6-(dihydrogen phosphate) (21) has also been synthesized (2) the reaction sequence makes use of 3-deoxy l 2,5 6-di-O-isopropylidene D-galactofuranose (16), a compound that can be easily prepared from D-glucose (2, 60). The mono-isopropylidene derivative (17) formed by partial hydrolysis of the di-ketal is converted into the 6-tosylate (18) by reaction with one molar equivalent of p-toluenesulfonyl chloride. From this the epoxide (19) is formed by reaction with sodium methoxide. Treatment of the anhydro sugar with an aqueous solution of disodium hydrogen phosphate (26) leads to the 6-phosphate (20)... 

Fio. 13.—Formation of an Anhydro Sugar and of o-Glyceric Acid from 2-Amino-2-deoxy-o-galactose Residues in a Teiohoic Acid. 

The bulky triphenylmethyl group can be introduced also at the sterically hindered axial position of 1,6-anhydro sugars. With 3 molar equiv. of the reagent at 85-90 °C for 24 h, more than 8% of 2-acetamido-l,6-anhydro-2-deoxy-3-0-trityl-P-D-gluco-pyranose (45) has been obtained [317] from (43). The 4-trityl ether [i.e., (44)] was, of course, the major product, just as in the case of tritylation of l,6-anhydro-2-0-p-toluenesulfonyl-P-D-glucopyranose [318] or, l,6-anhydro-2-0-benzyl-P-D-glucopyra-nose [229]. 

Ascarylose (94) and the (35) deuterium-labeled ascarylose were prepared starting from methyl a-L-rhamnopyranoside via the 2,3-anhydro sugar 120 (Scheme 34).204 Opening of the epoxide ring with lithium aluminum hydride in THF led selectively to the 3-deoxy derivative. If reduction was performed with lithium aluminum deuteride, the methyl (3S)-[32H]ascaryloside (3S)-[32H]119 was obtained. 

Oligomerization of a 7-amino-2,6-anhydro-7-deoxy-heptonic acid results in mimetics of (1 6)-linked sugars with a three-atom instead of a two-atom linker. The sulfated tetramer 24 (O Scheme 7) turned out to exhibit /x-molar activity in the protection of MT2 cells from HIV infection [33], and was also shown to provide heparanase inhibitory activity [34]. With different location of the amide bond, a still benzyl protected /3(1 6)-linked octamer of glucosyl-uronic acid-methyl amine (Gum [35]) 25 was synthesized [36]. 

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