C-2 Epimerization of aldonolactones promoted by magnesium iodide: a new way towards non-enzymatic epimerization.
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 MgI(2) 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.
Gratien
Julie
J
CEA, DSV, iBiTecS, Service de Chimie Bioorganique et de Marquage (SCBM), Bât 547, Gif sur Yvette F-91191, France.
Heck
Marie-Pierre
MP
Mioskowski
Charles
C
D007454:Iodides / Q000737:chemistry*; D007536:Isomerism; D007783:Lactones / Q000737:chemistry*; D017616:Magnesium Compounds / Q000737:chemistry*; D009005:Monosaccharides
D007454:Iodides; D007783:Lactones; D017616:Magnesium Compounds; D009005:Monosaccharides; C510205:magnesium iodide