1.6-Naphathyridines II. 2,3-Distributed derivatives and some new tricyclic ring systems†

A number of new 2- and/or 3-substituted 1,6-naphthyridines were prepared via Friedlander reactiona with 4-aminonicotinaldehyde and methylene compounds containing α-ketones, Methylene compounds with two reactive α-centers were also used. The facile conversion of the 1,6-naphthyridines into new tricylic ring system is reported.