Roles of Two Basic Nitrogen Atoms in 1-Substituted 4-(1,2-Diphenylethyl)piperazine Derivatives in Production of Opioid Agonist and Antagonist Activities.
To ascertain roles of the two basic nitrogenatoms in 1-substituted 4-[2,(3-hydroxyphenyl)-1-phenylethyl]-piperazine derivatives (1) in the expression of opioid agonist and antagonist activities, a methine group (CH) was isosterically substituted for nitrogenatom at the 1-position (N-1) in compound 1 to obtain 4-substituted 1-[2-(3-hydroxyphenyl)-1-phenylethyl]piperidine derivatives (2). Their analgesic