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

Article abstract of DOI:10.1016/S0040-4020(97)00847-8

2-Bromo-1-arylethylidenemalononitriles react with conjugated thiolaronitriles 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-h']dipyridines, their hydrogenated analogues, and pyrido[2',3':4,5]thieno[2.3-d]pyrimidine were synthesized.