Synthesis of new heterocycles containing more than one 1,2,3-thia or selenadiazole rings

摘要

The diketones 2a-d with different alkyl chain length are used for the synthesis of di-1,2,3-thia or selenadiazole derivatives 4a-d and 5a-d. The diketones 2a-d where prepared by a unique method through the reaction between the corresponding dibromoalkanes 1a-d and ethyl acetoacetate, which are transformed into the corresponding semicarbazone derivatives 3a-d. The di-1,2,3-thia or selenadiazole derivatives 4a-d and 5a-d were prepared from the semicarbazones derivatives 3a-d on oxidative cyclization with thionyl chloride and selenium dioxide respectively in high yield.