Some aspects of 1,4-diazaphenothiazine chemistry

Quinoxalino[2,3-b][1,4]benzothiazine 1 and its pyrazino-analogue 6 both give pairs of isomeric N-methyl derivatives. The N-methyl compounds 2 and 7 on oxidation with iodobenzene dichloride and other reagents give sulphoxides and sulphones (accompained by some ring substitution) but treatment of 6 with iodobenzene dichlorode gives benzothiazole-2-carboxamide 17. The action of sodium nitrite in acetic acid upon the thiazine 6 gives the 3-nitro derivative 25, substitution having occurred in the pyrazine ring; other nitrations are described.     

A synthesis of pyrrolo[3,4-c]pyridines via pyridyne intermediates

A synthesis of pyrrolo[3,4-c]pyridines from pyridyne intermediates is reported together with a study of the reactions of 2-methyl-2H-pyrrolo[3,4-c]pyridine (5) with oxidising and reducing agents.