Push‐pull‐Butadiene. VIII. Reaktionen von substituierten Penta‐1,4‐dien‐1,1,5,5‐tetracarbonitrilen

Push‐pull‐Butadienes. VIII. Reactions of Substituted 1,4‐Pentadiene‐1,1,5,5‐tetracarbonitriles 4‐Aryl‐2‐methylthio‐1,4‐pentadiene‐1,1,5,5‐tetracarbonitriles 1 react with bromine to give the nicotinonitriles 2. Compounds 2 and hydrazine hydrate yield the pyrazolo[3,4‐b]‐pyridines 7. Bis(methylthio)nicotinonitriles 9 are prepared by the treating of 2 with methanethiol in an alkaline solution. Compounds 1 can be converted with hydrobromic acid or hydrochloric acid to the nicotinonitriles 2a‐‐c and 2d‐‐f, respectively.