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Note | Regular issue | Vol 75, No. 8, 2008, pp.2005-2012
Published online, 28th March, 2008
DOI: 10.3987/COM-08-11355
■ Synthesis of Novel Pyrazolo[5,1-b][1,3]benzothiazoles: A New Pericyclic Pathway

Betül Tekiner-Gulbas, László Filák, Gyöngyvér Ágnes Vaskó, Orsolya Egyed, Ismail Yalçin, Esin Aki-Sener, Zuzsanna Riedl, and György Hajós*

*Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1025 Budpest, Pusztaszeri út 59, P.O. Box 17, Hungary

Abstract

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.