[Synthesis and analgesic activity of 1-substituted derivatives of 4-methoxycarbonyl-4-N-propionylanilinepiperidine].

In this paper, the synthesis and analgesic activities of a series of 1-substituted derivatives of N-[1-(2-phenylethyl)-4-methoxycarbonyl-4-piperidinyl]-N-propionylanil ine (4-methoxycarbonyl fentanyl) are reported. Preliminary pharmacological results showed that most compounds in this series exhibited typical morphine-like action and that replacement of beta-phenyl group in the 1-position of piperidine ring of 4-methoxycarbonyl fentanyl by some substituents e.g., some substituted vinyl groups, heterocyclic (or alcyclic) radicals, alkyl groups or N-methyl-anilino groups, can keep strong analgesic activity. Especially, some substituted vinyl groups were found to be effective groups which could replace 1-beta-phenyl group of 4-methoxycarbonyl fentanyl. Compounds N-[1-(3, 4-dimethyl-3-pentenyl)-4-methoxycarbonyl-4-piperidinyl]-N- propionylaniline(1321) and N-[1-(4-methyl-3-pentenyl)-4-methoxycarbonyl-4-piperidinyl]-N- propionylaniline(1302) exhibited higher analgesic activity than that of 4-methoxycarbonyl fentanyl.