Two Structural Alternatives of Glycosides of Vitamins: Pyranosic and Furanosic Ring of Sugar

Abstract

A  new  compound  has  been  synthesized,  D,L­α­tocopheryl­β­D­galactofuranoside,  as  a  new possible  metabolite  and  substrate for  β­galactofuranosidases.  The  synthesis included the following steps: the monosaccharide was heated in pyridine and then peracylated while still warm. Furanosic products, i. e.,  penta­O­benzoyl­αβ­D­galactofuranosides,  have  been  separated from the  pyranosic ones by fractional crystallization and characterized by chemical and physical methods. Bromination of the galactofuranosides mixture with hydrobromic acid produced the glycosylation donor, tetra­O­ benzoyl­α­D­galactofuranosyl  bromide.  Koenigs­Knorr  D­galactofuranosylation  of  D,L­α­ tocopherol,  by  using  cadmium  carbonate  as  promotor,  produced  D,L­α­tocopheryl­β­D­(2,3,5,6­ tetra­O­benzoyl)galactofuranoside. Protecting groups were removed by Zemplen saponification and the  galactofuranoside  purified  by  column  chromatography  on  silicagel.  The  new  synthesized compound was characterized by physical­chemical and chromatographical means.