SYNTHESIS OF NOVEL PYRAZOLO[5,1-b][1,3]BENZOTHIAZOLES:A NEW PERICYCLIC PATHWAY

摘要

2-Benzylbenzothiazoles were easily N-aminated by tosyl hydroxylamine, and the obtained N-amino salts were reacted with ethyl orthoformate to give new derivatives of the pyrazolo[5,1-b][1,3]benzothiazole ring system. 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 derivatives of the target ring system.