The regiospecific synthesis of 5- and 7-monosubstituted and 5,6-disubstituted 2-arylbenzothiazoles

The regiospecific synthesis of a range of antitumour 2-arylbenzothiazoles substituted in the benzothiazole ring is described. In this procedure a bromine atom situated ortho to the anilido nitrogen is used to direct a regiospecific cyclisation where, in the absence of bromine, a mixture of regioisomers is produced. The chemistry described is applicable to the synthesis of 2-arylbenzothiazoles bearing both electron-withdrawing (-NO2) and electron-donating (-NH2) substituents on the aryl ring.