On the influence of the C2-O2 and C3-O3 bonds in 4,6-O-benzylidene-directed β-mannopyranosylation and α-glucopyranosylation
On the influence of the C2-O2 and C3-O3 bonds in 4,6-O-benzylidene-directed β-mannopyranosylation and α-glucopyranosylation
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DOI：
10.1021/jo061417b
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发表时间：
2006-10-27
影响因子：
3.6
通讯作者：
Vinogradova, Olga
中科院分区：
文献类型：
--
作者：
Crich, David;Vinogradova, Olga
本文报道了4，6-O-亚苄基保护的2-脱氧阿拉伯糖甙、3-脱氧阿拉伯糖甙和3-脱氧核糖硫甙的合成，并研究了它们在1-苯亚磺酰基哌啶/三氟甲磺酸酐或二苯基亚砜/三氟甲磺酸酐活化下的糖基化反应。与分别为α-和β-选择性的相应的4，6-O-亚苄基保护的葡糖基和甘露糖基供体相反，在所有情况下观察到差的非对映选择性。这种差的选择性的原因进行了讨论，在葡萄糖基和甘露糖基的捐助者之间的相互作用的C2-O2和C3-O3键和这种相互作用的影响上的中间体糖基oxacarbenium离子的形成的容易程度。
The synthesis of 4,6-O-benzylidene- protected 2-deoxyarabino-, 3-deoxyarabino-, and 3-deoxyribothio-glycosides is described and their glycosylation reactions, with activation by either 1-benzenesulfinyl piperidine/trifluoromethansulfonic anhydride or diphenyl sulfoxide/trifluoromethanesulfonic anhydride, studied. In contrast to the corresponding 4,6-O-benzylidene- protected glucosyl and mannosyl donors, which are alpha- and beta-selective, respectively, poor diastereoselectivity is observed in all cases. The reasons for this poor selectivity are discussed in terms of the interaction between the C2-O2 and C3-O3 bonds in the glucosyl and mannosyl donors and of the influence of this interaction on the ease of formation of the intermediate glycosyl oxacarbenium ions.