Anomeric O-acylation of Kdo using alkyl and aryl isocyanates
Anomeric O-acylation of Kdo using alkyl and aryl isocyanates
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DOI：
10.1016/j.carres.2005.09.002
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发表时间：
2005-12-12
影响因子：
3.1
通讯作者：
Yamasaki, R
中科院分区：
文献类型：
--
作者：
Ichiyanagi, T;Yamasaki, R
为了开发一种方便的方法用于制备在还原末端携带功能间隔基的α-Kdo衍生物，我们分别使用Kdo和卤代烷基/芳基异氰酸酯作为亲核试剂和亲电子试剂研究了异头O-酰化。在DMAP存在下，Kdo衍生物与异氰酸2-氯乙酯反应，得到α-螺环产物（82%）和二聚异氰酸酯加合物的α-Kdo衍生物（10%）。与4-（氯甲基）苯基异氰酸酯的类似反应仅得到相应的α-螺环产物（81%）。核磁共振数据表明，烷基和芳基螺环产物的吡喃糖环均采用C-5（2）构象。因此，我们通过将Kdo衍生物与烷基和芳基异氰酸酯偶联来实现α-选择性异头O-酰化。(c)2005爱思唯尔有限公司保留所有权利。
To develop a convenient method for the preparation of an alpha-Kdo derivative carrying a functional spacer at the reducing end, we examined anomeric O-acylation using Kdo and halogenated alkyl/aryl isocyanates as nucleophile and electrophiles, respectively. Reaction of a Kdo derivative with 2-chloroethyl isocyanate in the presence of DMAP gave an alpha-spiro product (82%) and an alpha-Kdo derivative of a dimeric isocyanate adduct (10%). Similar reaction with 4-(chloromethyl)phenyl isocyanate gave only the corresponding a-spiro product (81%). The NMR data show that the pyranose rings of both the alkyl and aryl spiro products adopt the C-5(2) conformation. Thus, we accomplished alpha-selective anomeric O-acylation by coupling the Kdo derivative with alkyl and aryl isocyanates. (c) 2005 Elsevier Ltd. All rights reserved.