An Efficient Route to Pyridazino[4, 3-e][1, 3, 4]thiadiazines

Some new 3-(alkylsulfanyl)-7-chloro-1-phenyl-1H-pyridazino [4,3-e][1,3,4]thiadiazine were synthesized by treatment of the alkyl-2-phenylhydrazinecarbodithioates with 4-bromo-3,6-dichloropyridazine in alkaline acetonitrile. Orientation of the reaction has been determined by X-ray crystallography technique. The chlorine atom on the number 7 position of these products was replaced by secondary amines at reflux condition.