Comprehensive and Facile Synthesis of Some Functionalized Bis-Heterocyclic Compounds Containing a Thieno[2,3-b]thiophene Motif

A comprehensive and facile method for the synthesis of new functionalized bis-heterocyclic compounds containing a thieno2,3-b]thiophene motif is described. The hitherto unknown bis-pyrazolothieno2,3-b]thiophene derivatives 2a-c, bis-pyridazin othieno2,3-b]thiophene derivatives 4, bis-pyridinothieno2,3-b]thiophene derivatives 6a,b, and to an analogous bis-pyridinothieno2,3-b]thiophene nitrile derivatives 7 are obtained. Additionally, the novel bis-pyradazinonothieno2,3-b]thiophene derivatives 9, and nicotinic acid derivatives 10, 11 are obtained via bis-dienamide 8. The structures of all newly synthesized compounds have been elucidated by (1)H, (13)C NMR, GCMS, and IR spectrometry. These compounds represent a new class of sulfur and Nitrogen containing heterocycles that should also be of interest as new materials.