Compounds of the formula:-
or a salt thereof,
wherein "Het" is a group of the formula:-
in which R¹ is attached to position "a" or "b" of the benzene ring and R and R¹, which are the same, are -NHSO₂(C₁-C₄ alkyl), -NH₂ or -NO₂.
The compounds in which R and R¹ are -NHSO₂(C₁-C₄ alkyl) are cardiac antiarrhythmic agents. The compounds in which R and R¹ are -NO₂ or -NH₂ are synthetic intermediates.