Glycosyl ortho-Methoxybenzoates: Catalytically Activated Glycosyl Donors with an Easily Removable and Recyclable Leaving Group
Glycosyl ortho-Methoxybenzoates: Catalytically Activated Glycosyl Donors with an Easily Removable and Recyclable Leaving Group
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DOI：
10.1002/ejoc.201600747
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发表时间：
2016-11-01
影响因子：
2.8
通讯作者：
Jensen, Henrik H.
中科院分区：
文献类型：
--
作者：
Kristensen, Steffan K.;Salamone, Stephane;Jensen, Henrik H.
我们将-邻甲氧基苯甲酸酯描述为催化化学糖基化的货架稳定和实用的C-1核液，其中苯甲酸副产物可以很容易地去除，重新分离，并且在糖基化反应后可以回收利用。这种新型糖基供体可以被一系列启动子有效激活，包括Bi(OTf)(3)、Fe(OTf)(3)、TMSOTf （TMS =三甲基硅基）和三酸，催化剂负载低（< 10 mol-%）。该给体比类似苯甲酸盐、对甲氧基苯甲酸盐和对氰基-邻甲氧基苯甲酸盐给体表现出更高的反应活性。在与邻甲氧基苯甲酸酯供体的糖基化反应中，对于各种糖基受体，包括碳水化合物基仲醇，双糖产物的产率都很好。此外，β -选择性甘露糖基化与crh型供体在0℃至环境温度下实现，没有供体预激活。供体还用于一锅两步糖基化的第一步，以获得三糖；第二次偶联涉及与NIS/TMSOTf （NIS = n -碘琥珀酰亚胺）的巯基糖苷的活化。我们相信这为当前的协议提供了一个很好的替代方案。
We describe the beta-ortho-methoxybenzoate as a shelf stable and practical C-1 nucleofuge for catalytic chemical glycosylation in which the benzoic acid by-product can be easily removed, reisolated, and potentially recycled after the glycosylation reaction. This new type of glycosyl donor can be efficiently activated by a range of promoters, including Bi(OTf)(3), Fe(OTf)(3), TMSOTf (TMS = trimethylsilyl), and triflic acid, with low (< 10 mol-%) catalyst loadings. The donor shows higher reactivity than analogous benzoate, p-methoxybenzoate and p-cyano-o-methoxybenzoate donors. In glycosylation reactions with o-methoxybenzoate donors, the yields of disaccharide products were good to excellent for various glycosyl acceptors, including a carbohydrate-based secondary alcohol. Furthermore, beta-selective mannosylation was achieved with a Crich-type donor at 0 degrees C to ambient temperature, without donor preactivation. The donor was also used for the first step of a one-pot two-step glycosylation to obtain a trisaccharide; the second coupling involved activation of a thioglycoside with NIS/TMSOTf (NIS = N-iodosuccinimide). We believe that this offers a good alternative to current protocols.