S. D. Carter, G.W.H. Chesseman
1977
Citations
0
Influential Citations
15
Citations
Journal
Tetrahedron
Abstract
Abstract 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.