Conjugate addition of 2-thienylcarbonyl(thioacetanilides) (1) to arylmethylenemalononitriles (2) yielded 2-amino-1,4-diaryl-5-(2-thienylcarbonyl)-6-thioxo-1,4,5,6-tetrahydropyridine-3-carbonitriles (4), which when oxidised with HgO gave functionalised 2,6-dioxopiperidines (6), whereas with MCPBA they afforded pyrido[2,1-b]benzothiazole-2-carbonitrile derivatives (7).
