SYNTHESIS OF SOME NOVEL 2-PHENYLPYRIDAZINO[4,5-B][1,5]THIAZEPINES

Synthesis of some derivatives of the pyridazino[4,5-b][1,5]thiazepine ring system is reported. Thus, 8-methyl-2-phenyl-2,3,4,5-tetrahydro-5H -pyridazino [4,5-b][1,5]thiazepin-9(8H)-one (5) was prepared by an int ramolecular S-alkylation reaction, whereas the thiazepine ring of sulf one analogue 21, and that of the novel tricyclic pyrrolidino fused rin g system 22 was elaborated by an intramolecular C-alkylation reaction. Unexpected formation of bicyclic pyrido- and thiazine fused pyridazin e systems are also discussed.