2-bromo-1-arylethylidenemalononitriles - Convenient reagents for the regioselective synthesis of fused pyridines.

2-Bromo-1-arylethylidenemalononitriles react with conjugated thiolatonitriles to give products of regioselective S alkylation that can be subsequently involved in the Thorpe reaction. Resulting enaminoacrylonitriles form pyridine ring under base catalysis yielding thienodipyridines. According to this common scheme, functionally substituted thieno[3,2-b]pyridines, thiazolo[4,5-b]pyridines, thieno[3,2-b:4,5-b]dipyridines, their hydrogenated analogues, and pyrido[2',3':4,5]thieno[2,3-d]pyrimidine were synthesized. (C) 1997 Elsevier Science Ltd.