Pyridazine derivatives and related compounds, part 12: Synthesis of some pyridazino {[}4 `,3 `:4,5]thieno{[}3,2-d]-1,2,3-triazines

The syntheses of pyridazino{[}4',3':4, 5]thieno{[}3, 2-d]-1,2,3-triazinones 2, 3, 6, derivatives of the ring system thieno{[}2,3-c]pyridazine, have been accomplished by a diazotization reaction. Reaction of triazine 3 with phosphorous oxychloride led to 4-chloro derivative 7 which, on further displacement reactions, gives 4-substituted derivatives. All new compounds were characterized by elemental analyses and spectral data.