Reactions of 4-benzoyl-5-phenylamino-2,3-dihydrothiophene-2,3-dione and diaminomaleonitrile in the presence of alcohols as reactant and solvent

The one-pot synthesis of a novel class of 5-(2-alkoxy-2-phenyl-1-N-phenylthiocarbamoylethenyl)-6-oxo-1,6-dihydropyrazine-2,3-dicarbonitriles (2a–o) is achieved in moderate to good yields by the sequential reaction between 4-benzoyl-5-phenylamino-2,3-dihydrothiophene-2,3-dione, diaminomaleonitrile and alcohols.