Direct Experimental Characterization of the Ferrier Glycosyl Cation in the Gas Phase
Direct Experimental Characterization of the Ferrier Glycosyl Cation in the Gas Phase
复制标题
DOI：
10.1021/acs.orglett.0c03301
复制
发表时间：
2020-11-20
期刊：
影响因子：
5.2
通讯作者：
Pagel, Kevin
中科院分区：
文献类型：
--
作者：
Greis, Kim;Kirschbaum, Carla;Pagel, Kevin
Ferrier重排反应是药物合成的关键。虽然其机制在50多年前就被描述过，但中间体的结构仍然难以捉摸。已经提出了两种结构的费雷尔糖基阳离子：1，2-不饱和的阳离子，是共振稳定的吡喃糖环内的阳离子或稳定的邻乙酰基的邻位协助。使用氦纳米液滴和第一性原理密度泛函理论的气相低温红外光谱相结合，我们提供了第一个直接的结构表征的Ferrier阳离子。数据表明，乙酰化的葡萄糖醛和半乳糖醛都导致二氧戊环鎓型的糖基阳离子。
The Ferrier rearrangement reaction is crucial for the synthesis of pharmaceuticals. Although its mechanism was described more than 50 years ago, the structure of the intermediate remains elusive. Two structures have been proposed for this Ferrier glycosyl cation: a 1,2-unsaturated cation that is resonance-stabilized within the pyranose ring or a cation that is stabilized by the anchimeric assistance of a neighboring acetyl group. Using a combination of gas-phase cryogenic infrared spectroscopy in helium nanodroplets and first-principles density functional theory, we provide the first direct structural characterization of Ferrier cations. The data show that both acetylated glucal and galactal lead to glycosyl cations of the dioxolenium type.