N. Campillo et al., A NOVEL TETRACYCLIC SYSTEM CONTAINING THE 1,2,6-THIADIAZINE RING - SYNTHESIS, STRUCTURAL ASSIGNMENT AND TAUTOMERIC STUDIES, Heterocycles, 48(9), 1998, pp. 1833-1840
Condensation of 3,4,5-triamino-2H-1,2,6-thiadiazine 1,l-dioxide with p
hthalaldehyde afforded a tetracyclic system of thiadiazino[3'4':4,5]im
idazo[2,1-a]isoindole 2,2-dioxide. In order to establish the correct s
tructure it was necessary to use an N-15-labelled thiadiazine derivati
ve as starting material. Ab initio theoretical calculations and the On
sager model have been used to study annular tautomerism in this novel
structure.