[New heterocyclic systems for thiophene-2-thiolates--synthesis and biological activity].

Dicyanketendithiolae reacts with equimolar amounts of halogenmethans, substituted with electron withdrawing groups, to give thiophene-2-thiolates. These compounds are used for the preparation of thieno[2,3-b]thiophenes, including several functional groups in 2- and 5-position. Anellation of 1,3-oxazin-, pyrimidin-, 1,2,3-triazin- or 1,4-oxazepin-cycles give hitherto unknown tri- and tetracyclic ring systems. Some of synthetised compounds show biological activity.