No abstract

3‐Aryl‐1,2,4‐triazin‐5(2H)‐ones 1a‐c react with indoles 2a‐c in trifluoroacetic acid/chloroform or in boiling butanol or acetic acid to give 3‐aryl‐6‐(indolyl‐3)‐1,6‐dihydro‐1,2,4‐triazin‐5(2H)‐ones 3a‐g. Oxidation of the dihydro‐1,2,4‐triazin‐5(2H)‐ones 3a‐e afforded 6‐(indolyl‐3)‐1,2,4‐triazin‐5(2H)‐ones 4a‐e, products of nucleophilic substitution of hydrogen in 1a‐c. Refluxing 1b with N‐methylpyrrote 5b in butanol for an extended time resulted in the formation of 3‐(4‐chlorophenyl)‐6‐(1‐meuiylpyrrolyl‐2)‐1,2,4‐triazin‐5(2H)‐one 4h. The reaction of 1a‐c with indoles 2a‐c, pyrroles 5a,b, 1,3‐dimethyl‐2‐phenylpyrazol‐4‐one (8) and aminothiazoles 9a,b in acetic anhydride affords the 1‐acetyl‐3‐aryl‐6‐hetaryl‐1,6‐dihydro‐1,2,4‐triazin‐5(2H)‐ones 6a‐s. Reaction of 1a‐c with N‐methyl‐pyrrole 5b in acetic anhydride gives beside the 1:1 addition products 6h‐k also the 2:1 addition products 7a‐c.