2-Mercapto-4,6-disubstituted nicotinonitriles: versatile precursors for novel mono- and bis[thienopyridines]

A series of novel thieno[2,3-b]pyridines were prepared from the reaction of the appropriate bromoacetylbenzofurans or bromoacetylbenzothiazole with the corresponding pyridinethione derivatives in ethanolic sodium ethoxide at reflux. Moreover, new bis(thieno[2,3-b]pyridine) derivatives have also been synthesized by the reaction of the appropriate bis-bromoacetyl derivatives with the corresponding pyridinethiones in the presence of sodium ethoxide. Attempts to synthesize the target bis(thieno[2,3-b]pyridine) derivatives by bis-alkylation of the corresponding (thieno[2,3-b]pyridin-2-yl)(hydroxyphenyl)methanone with the appropriate dihaloalkanes using a mild base were unsuccessful.