9-amino-, 9-deoxy-, synthesis methyl glycoside

The preparation of several glucofuran [2, l-t/] oxazolines 35 and 36 from reaction of 2-amino-2-deoxy-D-glucose 34 with HF has been described. Compounds 35a and 35b are formed when the reaction is carried out in formic acid, whereas the orthoesters 36a-c are formed when the reaction is carried out using anhydrides. Further reaction of 35 and 36 with methanol gives methyl glycosides. Thus, 35 and 36 may hnd use as potential glycosyl donors for the synthesis of 2-amino-2-deoxy sugars (Scheme 8.14). " ... 

Dihydropyridine 429 was next used for the synthesis of methyl glycoside of 5-amino-5-deoxy-DL-ido-hexopiperidonose (445). In the first step, 429 was reacted with N-bromosuccinimide to afford two bromoacetates (439 and 440). The first bromoacetate (429) was deacetylated to the bromohydrin 441. Reaction with silver oxide followed by acetylation gave a rearranged diacetate 442 (which was certainly preceded by an epoxide). The 1-0-acetyl group in 442 could be readily replaced by a methoxy group to form 443. C -hydroxylation of the... 

In the course of the synthesis of 2-amino-2-deoxy-3,4-di-0-methyl-D-glucose, the 3-methyl ether of methyl 2-acetamido-2-deoxy-6-0-trityl-a-D-glucopyranoside was obtained as a secondary product on methylation with Purdie s reagents. Elimination of the trityl group afforded the same glycoside as that obtained by Neuberger. 

Amino-2-deoxy-D-glucose has been used for the synthesis of a glycoside of 6-epipurpurosamine (2,6-diamino-2,3,4,6,7-pentadeoxy-L-/yxo-heptose) which is a component of the antibiotic fortimicin A (Scheme 3). A nine-stage synthesis of methyl o-DL-purpurosaminide B has also been recorded which employed... 

The amide 24, an intramediate in synthesis of methyl 4,6-dideoxy-4-(3-deoxy-L-g(ycero-tetronamido)-a-D-truuinopyranoside, t-butyl-NA -dibenzyl-2-(l,2 5,6-di-0-isopropylidene-a-I>-allofuranose-3-yl)-L-glycirutle 25, 3 2-deoxy-2-hydroxyimino derivatives 26 and 27 of fi-D-arabino-hexopyranose, and 23,4,S-tMra-0-ace l-6-amino-6-deoxy-D-galactonolactam.9S TheN-glycosidic... 

Besides the 0-glycosides mentioned so far, also attention has been paid to the synthesis of N- and S-analogues. The p-nitrophenyl N-glycoside of a-N-acetylneuraminic acid has been prepared by silver carbonate-promoted reaction of 4,7,8,9-tetra-0-acetyl-2-chloro-2-deoxy-p-N-acetylneuraminic acid methyl ester with p-nitroaniline and subsequent deprotection (Privalova and Khorlin 1969). Treatment of the same precursor with sodium azide, followed by de-esterification, led to the formation of 2-azido-2-deoxy-a-N-acetylneuraminic acid (Supp et al. 1980). The same authors reported also the preparation of the p-form. The azides can readily be converted into the 2-amino derivatives of N-acetylneuraminic acid. Subsequently, the amino function has been benzoylated. Data on the syntheses of the methyl and p-nitrophenyl S-glycosides of a-N-acetylneuraminic acid have been presented by Privalova and Khorlin (1969), whereas Ponpipom et al. (1980) have described a method for the synthesis of 5-acetamido-2-S-[6-(5-cholesten-3p-yloxy)hexyl]-3,5-dideoxy-2-thio-p-D-g/vccro-D-ga/acto-2-nonulopyranosonic acid. 

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