Described herein is a process for the preparation of monofluoromethylated organic biologically active compounds using monofluoromethylated reagents. Fluticasone Propionate and Fluticasone Furoate can be prepared using, for example, S-monofluoromethyl-S-phenyl-2,3,4,5-tetramethylphenylsulfonium tetrafluoroborate as monofluoromethylating reagent instead of bromofluoromethane.