Well, you can use it instead of propionyl chloride or propionic anhydride to acylate 1-phenethyl-4-(N-phenylamino)-piperidine to get a nice fentanyl analog with an ED50 of 0.08 mg / kg. Propionyl chloride is suspicious (right?), so I think this is a good alternative.
Or you can use 2-furoyl chloride to the amine. That compound will certainly not be suspicious. Then the ED50 is 0.02 mg / kg.