The reaction of phenylhydrazine (I) with propionaldehyde (II) gives the corresponding hydrazone (III), which is condensed with phenyldiazoninum chloride (IV) to yield the formazan (V). The cyclization of (V) by means of BF3 in hot acetic acid affords 3-ethyl-1,2,4-benzotriazine (VI), which is finally oxidized to the target dioxide by means of H2O2 and trifluoroacetic anhydride in dichloromethane.

The reaction of phenylhydrazine (I) with propionaldehyde (II) gives the corresponding hydrazone (III), which is condensed with phenyldiazoninum chloride (IV) to yield the formazan (V). The cyclization of (V) by means of BF3 in hot acetic acid affords 3-ethyl-1,2,4-benzotriazine (VI), which is finally oxidized to the target dioxide by means of H2O2 and trifluoroacetic anhydride in dichloromethane.

The reaction of 2-nitroaniline (I) with cyanamide and HCl at 100 C, followed by a treatment with NaOH at the same temperature gives the benzotriazine N-oxide (II), which is diazotized with NaNO2 and HCl, followed by a treatment with POCl3 and dimethylaniline to yield the chloro derivative (III). The reaction of (III) with tetraethyltin and Pd(PPh3)4 in hot DME affords the ethyl derivative (IV), which is finally oxidized with trifluoroperacetic acid in dichloromethane to provide the target N1, N4-bis oxide compound.