Fluorinated Carbohydrates

Abstract

This chapter discusses the synthesis of fluorinated carbohydrates. It presents the methods for the preparation of glycosyl fluorides and a number of examples from the types of glycosyl fluorides. On prolonged treatment with hydrogen fluoride under various conditions and depending upon the nature of the carbohydrate derivative studied, acyloxonium ions at other parts of the molecule may arise. These ions may depend on the nature of the acyl group, and their formation is sometimes accompanied by 1,8-anhydro ring-formation, in the case of pyranoses. Treatment of the acylated glycosyl halide of the opposite anomeric configuration with silver fluoride in acetonitrile was the method initially developed for the synthesis of the less stable anomers. Peracetylated β- D -glucopyranosyl fluoride has also been obtained, in unspecified yield by the treatment of peracetylated 1, 6-anhydro-β- D -glucopyranosyl with hydrogen fluoride in acetic anhydride. The fluoride displacement of sulfonyloxy groups by potassium, or cesium, fluoride in l,2-ethanediol, and a variety of other solvents has frequently been used. The epoxide cleavage by fluoride ion is also elaborated in the chapter.