Studies on Heterocyclic Enaminonitriles, XVI. Reactions of 2‐Benzamido‐4,5‐dihydro‐3‐thiophene‐ and ‐3‐furancarbonitriles with Cyanomethylene Compounds

The reactions of 2‐benzamido‐4,5‐dihydro‐3‐thiophene‐ and ‐3‐furancarbonitriles ( 1 and 2 ) with ethyl or methyl cyanoacetate and malononitrile (2 equiv.) in the presence of sodium hydride (1 equiv.) in dimethyl sulfoxide at 140°C gave ethyl or methyl cyano[3‐cyano‐4,5‐dihydro‐2(3 H )‐thienylidene‐ and ‐furanylidene]acetates ( 3a or 3b and 4a or 4b ) and [3‐cyano‐4,5‐dihydro‐2(3 H )‐thienylidene‐ and ‐furanylidene]propanedinitriles ( 3c and 4c ). On the other hand, compound 2 reacted with malononitrile (2 equiv.) in the presence of sodium hydride (1 equiv.) in dimethylformamide at room temp. to give [(2‐amino‐4,5‐dihydro‐3‐furanyl)(benzamido)‐methylene]propanedinitrile ( 5 ). The same treatment of 2 with ethyl or methyl cyanoacetate followed by reaction with acetic anhydride gave ethyl or methyl 6‐acetoxy‐3‐benzamido‐2,4‐dicyano‐2‐hexenoate ( 6a or 6b ).