The diazonium salts were prepared in good yield from equimolar
mixture of corresponding primary aromatic amines (1a–e) and nitrous
acid according to previously described methods [26,27]. The prepared
diazonium salt solution was slowly added to a stirred solution of 5-(3-
hydroxybenzylidene)-2,4-thiazolidinedione (1) as coupling component
in alkali medium by adjusting the pH at 8–9 and the temperature was
maintained at 0–5 °C. The resulting mixture was stirred for 2–3 h in