Ring closure reactions of 3‐arylhydrazonoalkyl‐quinolin‐2‐ones to 1‐aryl‐pyrazolo[4,3‐<i>c</i>]quinolin‐2‐ones

Abstract

Abstract 4‐Hydroxy‐3‐arylhydrazonoalkyl‐2‐quinolones 6 or reactive derivatives such as 3‐arylhydrazonoalkyl‐4‐tosyloxy‐2‐quinolones 7 or 4‐chloro‐3‐arylhydrazonoalkyl‐2‐quinolones 14 , which are obtained via 3‐acyl‐4‐hydroxyquinolones 4, 10 or 3‐phenylarrmomethylene‐quinoline‐2,4‐diones 12 , cyclize in excellent yields to 1‐aryl‐pyrazolo[4,3‐ c ]quinolin‐4‐ones (11). The cyclization conditions were investigated by differential scanning calorimetry (DSC).