The synthesis of vitamin E sugar 1,2-orthoesters

In this study, 3,4,6-tri- O -acetyl-1,2- O -(1-tocopheroxyethylidene)-α- d -glucopyranose (sugar 1,2-orthoester) was synthesized with good and moderate yields in the presence of an N , N -diisopropylethylamine/tetrabutylammonium iodide system via a reaction of α-tocopherol with sugar halides. The utility of sugar α- and β-chlorides, α-bromides, and α-iodide in the synthesis of aryl (α-tocopherol, 2,2,5,7,8-pentamethylchroman-6-ol and 2,6-dimethylphenol) 1,2-orthoesters was investigated. The stereoselective formation of exo -1,2-orthoesters was confirmed using 1 H and 13 C NMR spectroscopy. Graphical abstract