4-anilino-N-phenethyl-piperidine (4-ANPP) is an analytical reference material categorized as a piperidinamine.
It is an intermediate in the synthesis of fentanyl from N-phenethyl-4-piperidone (NPP). As such, 4-ANPP has been used as a precursor for the manufacture of fentanyl and related opioids.
4-ANPP is used as a precursor for the manufacture of fentanyl-type drugs; it is also an impurity found in fentanyl preparations and is a known metabolite of acetyl fentanyl, butyryl fentanyl, furanyl fentanyl, acrylfentanyl , and fentanyl.
4-ANPP is regulated as a Schedule II compound in the United States.