Glycosyl fluorides preparation, from glycals

This Section deals with the methods of preparation of glycosyl fluorides generally (for the synthesis of glycosyl fluorides by addition reactions to glycals, see Section 11,6), and gives a number of examples from the types of glycosyl fluorides that have been prepared. 

Glycosyl phosphorodithioates 171 (Scheme 46), prepared by action of 0,0-dialkylphosphorodithioic acid on the corresponding glycals, were employed as glycosyl donors in the synthesis of 2-deoxydisaccharides. The glycosylations of primary and secondary acceptors in the presence of silver fluoride proceeded sluggishly (from 7 to 12 days) and the a-stereoselectivities were somewhat low, except in a few cases [151]. 

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