Abstract
In a previous paper, we described the formation of the 8, 5-diazaphenothiazino [8, 7-h]-phenothiazine derivative (2) by acetylation of 2, 3-dihydro-3-imino-4-methyl-4H-1, 4-benzothiazine (1a). This paper deals with the acetylation of the desmethyl derivative (1b). When a suspension of 1b in acetic anhydride was heated under reflux for 2 hr, the bis [1, 4] benzothiazino [3, 2-b ; 2', 3'-e] pyridine derivative (5a) was obtained instead of the expected analog of 2. The structure of 5a was assigned on the basis of infrared, nuclear magnetic resonance and mass spectral data, and microanalysis. Treatment of 5a with Raney Ni afforded the desulfurized compound 6, which was identical with an authentic sample prepared by acetylation of 2, 6-dianilino-4-picoline (7). Deacetylation of 5a was attempted, and the monoacetyl compound 5b and the deacetyl compound 5c were obtained.
