C-2 Epimerization of aldonolactones promoted by magnesium iodide: a new way towards non-enzymatic epimerization

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• 作者：Julie Gratien ; Marie-Pierre Heck ; Charles Mioskowski
• 关键词：Aldonolactone ; Mannonolactone ; Gluconolactone ; C-2 epimerization ; Magnesium iodide
• 刊名：Carbohydrate Research
• 出版年：2008
• 期刊代码：15_00086215
• 类别：ch
• 出版时间：14 January 2008
• 卷：343
• 期：1
• 页码：18-30
• 文件大小：597 K

摘要

The first example of a non-enzymatic C-2 epimerization of aldonolactones is reported. The reaction of 2,3,4,6-tetra-O-benzyl-d-gluconolactone or 2,3,4,6-tetra-O-benzyl-d-mannonolactone with MgI₂ in EtOH afforded their respective C-2 epimer. Studies conducted in EtOD showing the incorporation of a deuterium atom only at the C-2 position of the epimerized product reveal an epimerization rather than a racemization reaction. A mechanism involving a chelation with a magnesium species is proposed to explain this C-2 inversion reaction.