Stereoselective synthesis of 尾-d-GlcNAc-(1 鈫?#xa0;4)-d-Glc disaccharide starting from lactose

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• 作者：Lorenzo Guazzelli^&dagger ; ; Giorgio Catelani ; Felicia D&rsquo ; Andrea ; ^{felicia.dandrea@farm.unipi.it" class="auth_mail} ; Tiziana Gragnani
• 关键词：尾-d-GlcNAc-(1  ; &rarr ;   ; 4)-d-Glc disaccharide ; Lactose ; Epimerization ; Amination with inversion
• 刊名：Carbohydrate Research
• 出版年：31 March, 2014
• 年：2014
• 卷：388
• 期：Complete
• 页码：44-49
• 全文大小：586 K

文摘

The stereoselective preparation of the 尾-d-GlcNAc-(1 鈫?#xA0;4)-d-Glc disaccharide starting from known 4-O-[6-O-(1-methoxy-1-methylethyl)-3,4-O-isopropylidene-尾-d-talopyranosyl]-2,3:5,6-di-O-isopropylidene-aldehydo-d-glucose dimethyl acetal (2), in turn easily obtained from lactose, is reported. Key steps of this new procedure, that avoids the glycosylation reaction, are (a) a first epimerization at C-4鈥?through an unusual procedure involving a completely stereospecific hydroboration-oxidation of the enol ether group of the hex-4-enopyranoside 4, obtained from 3 by base promoted acetone elimination, (b) an amination with inversion by S_N2 reaction on an imidazylate intermediate, and, finally, (c) N-acetylation followed by complete deprotection.