Synthesis of New Thieno[2,3-b:5,4-c′]dipyridines

Summary.

 We describe the formation of thieno[2,3-b:5,4-c′]dipyridines from 5,6-dihydropyridine-2(1H)-thiones. The two-step reaction mechanism was revealed by isolation of an intermediate. The oxo and thioxo groups of the obtained tricyclic compounds were hydrogenated selectively. The structures of all new compounds were elucidated by NMR experiments.