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

Abstract

AbstractThe 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(3H)‐thienylidene‐ and ‐furanylidene]acetates (3a or 3b and 4a or 4b) and [3‐cyano‐4,5‐dihydro‐2(3H)‐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). magnified image