Mn(Ⅲ)-Promoted Synthesis Of 2-Substituted Benzothiazoles Under Microwave Irradiation

Benzothiazole is a privileged bicyclic ring system. Due to their potent antitumor activity and other important pharmaceutical utilities, the synthesis of these compounds is of considerable interests.In this thesis, we designed and synthesized a series of thiobenzanilides and thioureas, which were readily prepared from commercially available benzanilide by sulfurization. These compounds were reacted with Mn(OAc)₃.2H₂O in glacial acetic acid under microwave irradiation to afford 2-arylbenzothiazoles (4a-h) , 2-benzoylbenzothiazoles (6a-f), 2-acetoxylbenzothiazoles (8a-d), and 2-benzoylamidobenzothiazoles (10a-e). Their structures were confirmed by ¹H NMR, ¹3C NMR and HRMS spectra. Based on these reactions, we also proposed a rational mechanism for manganese (III) triacetate-promoted cyclization reactions.