Organic heterocyclothiazenes. Part 2. Reaction of tetrasulphur tetranitride with phenylacetylene and diphenylacetylene

Abstract

The reaction of S₄N₄ with diphenylacetylene in boiling toluene has been found to give 3,4-diphenyl-1,2,5-thiadiazole (1) as the major product and 3,5-diphenyl-1,4,2,6-dithiadiazine (4), a new heterocyclic system, as a minor product. The same reaction with phenyacetylene gives 3-phenyl-1,2,5-thiadiazole (12) and the novel 1,3,2-dithiazolylimine (16), the first example of this mesoionic ring. These new structures correct literature assignments. Reaction mechanisms are proposed for the formation of the products.