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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.

Push-pull-Butadienes. VI. Synthesis of Substituted Nicotinonitriles 2-Aryl-4,4-bis(methylthio)-1,3-butadiene-1,1-dicarbonitriles 1 react with N-bromosuccinimide or sulphuryl chloride to give 3-bromo- and 3-chloro-butadienedicarbonitriles 3, respectively. Compounds 1 or 3 can be converted with methanethiol in alkaline solution to 4-aryl-2,6-bis(methylthio)nicotinonitriles 2. Butadienedicarbonitriles 3 and sodium alkoxide yield alkoxynicotinonitriles 5. 4-Aryl-2,6-dibromo- and 2-bromo-5-chloro-nicotinonitriles 8, respectively, are prepared by treating 1 or 3 with bromine. Nicotinonitriles 8 react with hydrazine hydrate to yield pyrazolo[3,4-b]pyridines 12. Treatment of butadienedicarbonitriles 3 with sulphuryl chloride gives 2-aryl-3-bromo- and 3-chloro-4-chloromethylthio-4-methylthio-1,3-butadiene-1,1-dicarbonitriles 17, respectively. The structures of the prepared compounds are in agreement with spectroscopic data.