Synthesis of 7-substituted 3-aryl-1,6-naphthyridin-2-amines and 7-substituted 3-aryl-1,6-naphthyridin-2(1H)-ones via diazotization of 3-aryl-1,6-naphthyridine-2,7-diamines

Abstract

The preparation of 3-aryl-7-halo-1,6-naphthyridin-2-amines and 3-aryl-7-halo-1,6-naphthyridin-2(1H)-ones from the diazotization of 3-aryl-1,6-naphthyridine-2,7-diamines is reported. The reactions were investigated in various solvents (concentrated HCl, 50% HBF₄, 70% HF–pyridine, 20% and 90% H₂SO₄, dilute HCl, and neat TFA). By appropriate choice of solvent and other conditions, good yields of the target compounds could be obtained, although in some cases a variety of different side products was also produced. Subsequent displacement of the 7-halogen substituents with alkylamines provides a route to more complex 7-substituted 1,6-naphthyridine derivatives that are potential tyrosine kinase inhibitors.