4-ANPP

4-ANPP, also known as 4-anilino-N-phenethylpiperidine (4-ANPP), 4-aminophenyl-1-phenethylpiperidine, or despropionyl fentanyl,^[3] is a direct precursor to fentanyl and acetylfentanyl. It is commonly found as a contaminant in samples of drugs containing fentanyl, which may include samples represented by the supplier as heroin or other opioids.^[4] It is not psychoactive and is present only as a result of improper chemical purification.

Quick facts Names, Identifiers ...

4-ANPP

Names
Preferred IUPAC name N-Phenyl-1-(2-phenylethyl)piperidin-4-amine
Other names desproprionyl fentanyl; 4-anilino-N-phenethylpiperidine; 4-ANPP; ANPP
Identifiers
CAS Number	21409-26-7
3D model (JSmol)	Interactive image
Abbreviations	ANPP
ChemSpider	87058 Y
ECHA InfoCard	100.169.974
EC Number	642-161-5
PubChem CID	88890
UNII	Q88EHD0U8G
CompTox Dashboard (EPA)	DTXSID40175680
InChI InChI=1S/C19H24N2/c1-3-7-17(8-4-1)11-14-21-15-12-19(13-16-21)20-18-9-5-2-6-10-18/h1-10,19-20H,11-16H2 Key: ZCMDXDQUYIWEKB-UHFFFAOYSA-N
SMILES C1CN(CCC1NC2=CC=CC=C2)CCC3=CC=CC=C3
Properties
Chemical formula	C19H24N2
Molar mass	280.415 g·mol−1
Legal status	AU: S9 (Prohibited substance) BR: Class D1 (Drug precursors)[1] UK: Scheduled Precursor US: Schedule II UN: International Red List[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

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4-ANPP is useful in the synthesis of pharmaceuticals, primarily fentanyl and related analogs. Paul Janssen (founder of Janssen Pharmaceutica) first synthesized fentanyl in 1960 using a similar method, with Benzylfentanyl as an intermediate.^[5] The following synthesis, developed by an individual under the pseudonym of Siegfried, involves the reductive amination of N-phenethyl-4-piperidinone (NPP) with aniline to make to 4-ANPP. This product is reacted with propionyl chloride or acetyl chloride to form either fentanyl or acetylfentanyl.