Synthesis and fungicidal activity of 1,4-dithiino[2,3-b]quinoxaline-2,3-dicarbonitriles

A series of eleven 1,4-dithiino2,3-b]quinoxaline-2,3-dicarbonitriles was prepared by reaction of 2,3-dichloroquinoxalines with disodium (2)-2,3-dimercapto-2-butenedinitrile in N,N-dimethylformamide. These products were tested for in-vitro fungicidal activity by a Minimum Inhibitory Concentration (MIC) method. Several of these compounds showed broad-spectrum fungicidal activity. The activity exhibited by these compounds was greatly dependent upon the substituents of the quinoxaline ring, with the nitro-substituted derivatives showing the highest levels of antifungal activity. None of the compounds prepared, however, showed fungicidal activity comparable to that of the commercial fungicides screened.