[摘要]：2-Benzylbenzothiazoles were easily N-aminated by tosyl hydroxylamine, and the obtained N-amino salts were reacted with Et orthoformate to give new derivs. of the pyrazolo[5,1-b][1,3]benzothiazole ring system, I (R = H, Me, Br, Cl, F, NO2). Mechanistic considerations suggest that the ring closure reaction proceeds via deprotonation of the N-amino salt followed by electrocyclization to provide the tricyclic ring system. The procedure opens an easy access to variously substituted derivs. of the target ring system.
