9-deoxy-, 9-iodo-, synthesis

Shaw synthesis, 3, 109 Uridine, 2 -deoxy-5-iodo-as pharmaeeutical, 1, 160 Uridine 5 -monophosphate biosynthesis, 1, 88 Uridylic acids occurrence, 3, 142 Urispas... 

The synthesis of halodeoxy sugars has also been achieved by reaction of sugar phosphorodiamido and phosphonamido derivatives with alkyl halides (83). Heating equimolar amounts of 6-(tetraethylphosphoro-diamido)-l,2 3,4-di-0 isopropylidene-D-galactose with methyl iodide (and benzyl bromide) at 140°C. for 4 hours afforded the 6-deoxy-6-iodo (74b) (75%) and 6-bromo-6-deoxy (74c) (56%) derivatives, respectively. 

W. S. Fyvie, M. Morton, and M. W. Peczuh, Synthesis of 2-iodo-2-deoxy septanosides from a D-xylose-based oxepine Intramolecular cyclization in the absence of a glycosyl acceptor, Carbohydr. Res., 339 (2004) 2363-2370. 

The facile formation of the iodo compound, and the subsequent reduction with tributyltin hydride opens a new access to 2-amino-2,3-dideoxy-D-glucose (D-lividosamine) present in various aminoglycoside antibiotics [92], The same strategy been used in the synthesis of C-lO -C-l fragment of boromycin [93]. Displacement of the C-3 imidazylate ester of a 2-azido-2-deoxy-a-D-altropyranose derivative with benzoate occurred readily [94], compared with the corresponding tosylate [95],... 

N. K. Kochetkov, A. I. Usov, and K. S. Adamyants, Synthesis and nucleophilic substitution reactions of some iodo-deoxy sugars, Tetrahedron 27 549 (1971). 

The method employing triphenyl phosphite methiodide, as adapted to carbohydrates,130 has been used for the synthesis of protected 4-deoxy sugars. From methyl 2,3-di-0-methyl-6-0-p-tolylsulfonyl-a-D-glucoside and the corresponding D-galactoside, epimeric 4-iodo derivatives were obtained these were both reduced to methyl 4-deoxy-2,3-di-0-methyl-b-0-p-tolyl-sulfonyl-a-D-zj/Zo-hexoside. 

The synthesis of a member of this class of deoxy sugars was accomplished in 1950. The then well-known ethyl 2,3-dideoxy-a-D-en/l/iro-hex-2-enopyranoside was reduced and the product was converted into ethyl 2,3,0-trideoxy-4-O- (methylsulfonyl) -a-D-eryfAro-hexopyranoside by way of the 4,6-dimethanesulfonate. During this work, it was found that, when the dimethanesulfonate of the unsaturated derivative is treated with sodium iodide in the cold, a selective displacement at C-4 occurs, no doubt due to the activated allylic system. The resulting 4-iodo derivative could... 

For the synthesis of the D-C portion, two different concepts were followed either by modification of laminaribiose (166) [89] or by a stereospecific P, 1 ->3-glycosylation [20]. Laminaran is isolated from seaweeds or from Poria cocos Wolf, degraded by selective acetolysis, and the lower oligomers separated by preparative HPLC [90]. Following acetylation, the heptaacetyl laminaribiosyl bromide is prepared and transformed into the disaccharide glycal 167 by the classical approach in 93 % yield. The 2-deoxy-2-iodo-a-glycoside is formed by application of the NIS procedure after deprotection and subsequent 4,6-0-benzylidenation, the precursor 168 for the radical formation of the 6,6 -dibromo-6,6 -dideoxy derivative is at hand. This compound may be further reduced to methyl-3-0-(P-D-chinovosyl)-a-D-olivoside (169). 

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