XtalFluor-E, [Et2NSF2]BF4, is best known as a useful, versatile and inexpensive commercially available reagent for the deoxyfluorination of carbonyl compounds and alcohols. Although XtalFluor-E is commonly used in combination with an exogenous fluoride source as a deoxofluorinating reagent, it has also been widely employed in other chemical transformations such as dehydration, cyclodehydration, ring expansion, formylation, and proto-functionalization, etc.
