Reaction of 5-halo-1,2,3-thiadiazoles with arylenediamines as a new approach to tricyclic 1,3,6-thiadiazepines

A multistep reaction of 5-halo-1,2,3-thiadiazoles and 1,2-phenylenediamines provides a new route to fused 1,3,6-thiadiazepines. The overall process consists of the known stepwise formation of 5-[1-(2-aminophenyl)-1,2,3-triazol-5-ylsulfanyl]-1,2,3-thiadiazole, and a novel ring transformation which involves the Smiles and Dimroth rearrangements followed by an intramolecular nucleophilic substitution of the thiol group, affording di[1,2,3]triazolo[1,5-a:5',1'-d]-[3,1,5]benzothiadiazepines. The influence of the substituents on the 1,2,3-thiadiazole and phenyl rings on this reaction was discussed.