Copper-catalyzed amination of (bromophenyl)ethanolamine for a concise synthesis of aniline-containing analogues of NMDA NR2B antagonist ifenprodil

Abstract

An operationally simple and concise synthesis of anilinoethanolamines, as NMDA NR2B receptor antagonist ifenprodil analogues, was developed via a copper-catalyzed amination of the corresponding bromoarene. Coupling was achieved with linear primary alkylamines, alpha,omega-diamines, hexanolamine and benzophenone imine, as well as with aqueous ammonia, in good yields using CuI and N,N-diethylsalicylamide, 2,4-pentadione or 2-acetylcyclohexanone as catalytic systems. Amination with ethylene diamine was efficient even in the absence of an additive ligand, whereas no reaction occurred with ethanolamine whatever the conditions used. The anilinoethanolamines were evaluated as NR2B receptor antagonists in a functional inhibition assay. Aminoethylanilines displayed inhibition effects close to that of ifenprodil.