Synthesis of novel functionalized bi- and oligopyridines

An annelation reaction is presented in which 1,3-cyclohexanedione (1) and M annich bases 6a,b are used for the preparation of functionalized bipyridine s 12a, 13a, 14a and dihydropyridine derivatives 10b, 11b. All these product s possess a keto group which will allow further transformations. The same c oncept was applied for the synthesis of the S-shaped terpyridine 25. The re action of the Mannich base 21 with 1,3-cyclohexanedione yielded the heptacy clic terpyridine 22, which is a key intermediate for the synthesis of toran ds and other tridentate clefts. The ketone 12a was used for the synthesis o f the quaterpyridine 26.