α-N-acetylmannosamine (ManNAc) synthesis via rhodium(II)-catalyzed oxidative cyclization of glucal 3-carbamates
α-N-acetylmannosamine (ManNAc) synthesis via rhodium(II)-catalyzed oxidative cyclization of glucal 3-carbamates
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DOI：
10.1021/jo0500129
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发表时间：
2005-05-13
影响因子：
3.6
通讯作者：
Rojas, CM
中科院分区：
文献类型：
--
作者：
Bodner, R;Marcellino, BK;Rojas, CM
在Rh-2（OAc）（4）存在下，将葡糖醛3-氨基甲酸酯1和7与二乙酸碘苯或碘酰苯进行氧化环化，得到甘露糖胺2-N，3-O-恶唑烷酮。与iodosobenzene，掺入4-戊烯-1-醇提供了一个容易分离的异头混合物的n-戊烯基糖苷，与异头表现出显着的差异，作为糖基供体的反应性。糖恶唑烷酮的N-酰化导致用于各种2-甘露糖胺框架的制备的α-选择性糖基供体。或者，将N-Cbz 2-甘露糖胺恶唑烷酮的异头正戊烯基糖苷分别转化为恶唑烷酮开环衍生物28 α和28 β。这些用作立体会聚糖基供体，并且α-连接的产物容易地前进到各种N-乙酰甘露糖胺（ManNAc）框架，使用分子内O -> N乙酰基转移作为最后步骤。
Glucal 3-carbamates 1 and 7 underwent oxidative cyclization with iodobenzene diacetate or iodosobenzene in the presence of Rh-2(OAc)(4), providing mannosamine 2-N,3-O-oxazolidinones. With iodosobenzene, incorporation of 4-penten-1-ol provided a readily separable anomeric mixture of n-pentenyl glycosides, with the anomers exhibiting pronounced differences in reactivity as glycosyl donors. N-acylation of the sugar oxazolidinones led to a-selective glycosyl donors for the elaboration of various 2-mannosamine frameworks. Alternatively, the anomeric n-pentenyl glycosides of N-Cbz 2-mannosamine oxazolidinones were converted separately to oxazolidinone-opened derivatives 28 alpha and 28 beta. These served as stereoconvergent glycosyl donors, and the a-linked products were readily advanced to a variety of N-acetylmannosamine (ManNAc) frameworks, using an intramolecular O -> N acetyl transfer as the final step.