1-Boc-4-AP

1-Boc-4-AP (tert-butyl 4-(phenylamino)piperidine-1-carboxylate) is a compound used as an intermediate in the manufacture of fentanyl, as well as various related derivatives such as butyrylfentanyl, furanylfentanyl, benzylfentanyl and homofentanyl, among others. It is an N-protected derivative of 4-anilinopiperidine which can be readily converted to fentanyl or related analogues in several straightforward synthetic steps. It was classified as a DEA List 1 Chemical in 2022, and is also controlled in various other jurisdictions. Its possession, sale and importation are consequently heavily regulated throughout much of the world. 1-Boc-4-AP has also been identified as an impurity in other designer drug products, though it is unclear if it has any pharmacological activity in its own right.