Ring Expansion of N-Aminobenzothiazolium Salts to Benzothiazines and Benzothiadiazines

László Filák,1 Betül Tekiner-Gulbas,2 Zsuzsanna Riedl,1 Gyöngyvér Ágnes Vaskó,1 Orsolya Egyed,1 Ismail Yalçin,2 Esin Aki-Sener2 and György Hajós1,*

1 Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út 59, H-1025 Budapest, Hungary
2 Ankara University, Faculty of Pharmacy, TR-06100 Tandogan, Ankara, Turkey

* Corresponding author: E-mail: ghajos@chemres.hu

Abstract
N-amino-2-benzylbenzothiazinium salts when reacted with aldehydes were found to undergo ring expansion reactions to give either benzothiadiazines or benzothiazines. This ambident reactivity was found to be influenced by the conjugative nature of the aldehyde used.

Keywords: Ring expansion, thiadiazine, thiazine, ambident reactivity, reaction mechanism