The interaction of 2-thienylidene derivatives of malononitrile and cyanothioacetamide with methylene active nitriles gives 2,6-diamino-3,5-dicyano-4-(2-thienyl)-4H-thiopyran which is smoothly recrystallized into 6-amino-3,5-dicyano-4-(2-thienyl)-2-(1H)-pyridinethione. The latter is easily alkylated at the sulfur atom by alpha-halocarbonyl compounds. This reaction was used in the synthesis of 3,6-diamino-4-(2-thienyl)thieno[2,3-b]pyridines.
The interaction of 2-thienylidene derivatives of malononitrile and cyanothioacetamide with methylene active nitriles gives 2,6-diamino-3,5-dicyano-4-(2-thienyl)-4H-thiopyran which is smoothly recrystallized into 6-amino-3,5-dicyano-4-(2-thienyl)-2-(1H)-pyridinethione. The latter is easily alkylated at the sulfur atom by alpha-halocarbonyl compounds. This reaction was used in the synthesis of 3,6-diamino-4-(2-thienyl)thieno[2,3-b]pyridines.