RING-OPENING OF [1,2,3]TRIAZOLO[1,5-A]PYRAZINIUM SALTS - SYNTHESIS AND SOME TRANSFORMATIONS OF A NOVEL TYPE OF 2-AZA-1,3-BUTADIENES

The synthesis of 1,3-disubstituted [1,2,3]triazolo[1,5-a]pyrazinium sa lts 6 and subsequent ring opening induced by the reaction with pyrroli dine provides a facile access to 4-(1-pyrrolidino)-1- ([1,2,3]triazol- 5-yl)-2-aza-1,3-butadienes 7, a new type of 2-aza-1,3-butadienes. Comp ounds 7 proved to be suitable starting materials for further ring form ation reactions. (C) 1997 Elsevier Science Ltd.