Microwave-assisted one-pot two-step imine formation–hetero-Diels–Alder–detosylation/aromatization sequence: direct access to dibenzo[b,h][1,6]naphthyridines

Abstract

A microwave-assisted, copper-catalyzed, one-pot, two-step reaction is established to access functionalized [1,6]naphthyridines in high yields (up to 96%) starting from 2-(N-propargylamino)benzaldehydes and arylamines. This rapid and operationally simple sequential reaction allowed the construction of two new heterocyclic rings and three new (2 C–C and 1 C–N) bonds in a single synthetic operation. This reaction tolerated various electron-donating and electron-withdrawing substituents well and delivered the desired products in a shorter reaction time under microwave irradiation. This reaction proceeds through a sequential imine formation, intramolecular [4 + 2] hetero-Diels–Alder reaction, and air oxidation, followed by detosylation–aromatization steps.