DEVELOPMENT OF THE NEW ORGANIC REACTION BY USING NEW LEWIS ACID, BF_2(Otf)

我们发现了一种新的路易斯酸，它与Me_3SiOTf以1：1的比例形成BF_3-OEt_2络合物，在乙腈中是有机合成中最常用和最常用的Lewis酸。通过1H-核磁共振、19&gt；F-核磁共振和11&gt；B-核磁共振的测定，确定了新生成的Lewis酸的结构为BF_2(OTF)。从这些核磁共振测量结果中，最重要的信息是Me_3SiF的检测。分子香料的生成表明，在乙腈中，BF3-OEt2络合物与Me_3SiOTf之间发生了快速的易金属反应。它发现这种新的刘易斯酸非常有用。特别是对含有游离羟基(无保护基团)的几种甲基吡喃糖衍生物iDose、葡萄糖和半乳糖，有效地进行了高度立体控制的C-烯丙基糖苷反应。

We found a new Lewis acid which were easily generated from BF_3-Oet_2 complex and Me_3SiOTf in 1:1 ratio, as the most general and popular Lewis acid in organic synthesis, in acetonitrile. Structure of the newly generated Lewis acid were determined as BF_2(Otf) by measurement of ^1H-NMR, ^<19>F-NMR abd ^<11>B-NMR. The most important information from those NMR measurement results was detection of the Me_3SiF. Generation of the molecular spices indicates that transmetalation reaction take place quickly between BF_3-Oet_2 complex and Me_3SiOTf in acetonitrile.This newly developed Lewis acid, as BF_2(Otf), was examined toward some Lewis acid mediated organic reactions. It found that this new Lewis acid was very useful. Especially, highly stereocontrolled C-allylglycosidation reaction efficiently took place toward some kinds of methyl pyranose derivatives, idose, glucose and galactose, with free hydroxyl groups (no protecting groups)