Synthetic approaches to tetrahydro-2,7- and -1,6-naphthyridines

[Display omitted] •Tetrahydro-2,7- and -1,6-naphthyridines multigram synthesis.•Stille cross-coupling reaction of bromopicolines.•From bromopicolines to 2,7-naphthyridines. Three new tetrahydronaphthyridines were prepared starting from readily available 3-bromo-picolines. The key step of the proposed strategy consists of reduction of the imine prepared by intramolecular reaction of the acyl and amine groups. The amine group was introduced via deprotonation of the methyl group in bromopicoline, its reaction with dimethylcarbonate, reduction to the corresponding alcohol and Mitsunobu reaction with phthalamide. The acyl group was placed at the bromine position via the Stille cross-coupling reaction of tributyl(1-ethoxyvinyl)stannane followed by hydrolysis. The proposed chemical sequence allowed the multigram preparation of tetrahydro-2,7- and 1,6-naphthyridines.