1,2,4‐triazines. 7 . Regioselective n2‐amination of 3‐methylthio‐1,2,4‐triazin‐5(2 H )‐ones.A novel synthesis of [1,2,4]triazolo[2,3‐ b ][1,2,4]triazinones and ‐triazine

A regioselective synthesis of 2‐aminotriazinones 6a‐d is reported, by reaction of 3‐methylthio‐1,2,4‐triazinones 5a‐d with O ‐(2,4‐dinitrophenyl)hydroxylamine (2) as an amino‐transfer agent. A spectroscopic study and an unequivocal synthesis of 2‐amino‐4‐methyl‐6‐phenyl‐1,2,4‐triazinedione ( 11a ) has shown the site of amination to be N2 of the 1,2,4‐triazinone ring. Subsequent reaction of 2‐amino‐1,2,4‐triazinones 6a‐b with amines, followed by ring closure with aliphatic acids provided [1,2,4]triazolo[2,3‐ b ][1,2,4]triazine‐7(1 H )ones 13a‐e. Conversion of [1,2,4]triazolo[2,3‐ b ][1,2,4]triazinone 13c to unsubstituted [1,2,4]triazolo[2,3‐6][1,2,4]triazine (15) was attained.