Synthesis of 5-membered heterocycles and related compounds.

Some 1-(2, 4-dichlorophenoxy and 2, 4, 5-trichlorophenoxy) acetyl-4-arylthiosemicarbazides were prepared from corresponding chlorophenoxyacetohydrazide. The resulting thiosemicarbazides were cyclised into 1, 3, 4-thiadiazoles and 5-mercapto-1, 2, 4-triazoles under different reaction conditions. The mercapto compounds were converted into sulphides and sulphones. N'-arylidene (2, 4-dichlorophenoxy) acetohydrazides and 5-substituted-1, 3, 4-oxadiazole-2-thiones were also prepared from (2, 4-dichlorophenoxy and 2, 4, 5-trichlorophenoxy) acetohydrazides separately and were subjected to Mannich reaction. Some of these compounds were evaluated as fungicides against Aspergillus niger.