Organic heterocyclothiazenes. Part 7. Chemistry of 1,3,5,2,4,6-trithiatriazepines

Abstract

Methyl trithiatriazepine-7-carboxylate (1), obtained from tetrasulphur tetranitride and dimethyl acetylenedicarboxylate, is hydrolysed to the carboxylic acid (3) which is decarboxylated in boiling dioxane to give the parent 1,3λ⁴δ²,5,2,4,6-trithiatriazepine (4). Trithiatriazepine (4) is a remarkably stable 10π aromatic system similar to, although less polar than, the trithiadiazepine(2b). The triazepine (4) is less reactive towards electrophilic substitution than the diazepine (2b) but it can be nitrated with nitronium tetrafluoroborate, and brominated with N-bromosuccinimide in acetonitrile at 110 °C. The thermal stability of compounds (2b) and (4) suggests that the unknown sulphur nitride trithiatetrazepine (8) would be thermodynamically stable.