Dithieno‐1,4‐thiazines. Part I

The synthesis of the first dithieno[2,3‐ b : 2′,3′‐ e ]‐1,4‐thiazine is described, this compound was prepared by condensation of 3‐thiophenethiol with methyl 2‐bromo‐3‐nitrothiophene‐5‐carboxylate followed by reduction, acylation, bromination with NBS and ringclosure with Cu, K 2 CO 3 in nitrobenzene. A thieno‐1,4‐benzothiazine was prepared in the same way. These compounds were synthesized in order to study the suggested correlation between charge‐transfer complexes vs. physiological activity.