The access to a new family of unusual 4-fluorinated pyrazoles bearing acetal moities at the 3- or 5-position has been achieved by electrophilic fluorination using Selectfluor® with yields up to 67%. The unconverted starting material can be recovered and recycled. This reaction has been successfully applied to the formal synthesis of a key intermediate in the synthesis of neprilysin inhibitors with 42% overall yield (5 steps).