Reactions of N-Aminopyrazoles with Halogenating Reagents and Synthesis of 1, 2, 3-Triazines

Reactions of N-aminopyrazoles with halogenating reagents (Cl2, Br2, I2, BrCl, ICl, IBr, N-chlorosuccinimide, and N-bromosuccinimide) were examined. Some of these reagents preferentially lead to oxidation of the amino group to give the corresponding 1, 2, 3-triazines as major products, while others mainly gave either or both of 1-amino-4-halopyrazoles and 5-halo-1, 2, 3-triazines as the result of halogenation of the 4-position of the pyrazole ring prior to the oxidation of the amino group. In some cases, the oxidation of the amino group and the halogenation of the pyrazole ring proceeded concurrently to form not only the unhalogenated triazines but also the l -amino-4-halopyrazoles and the 5-halotriazines. Various reagents and reaction conditions were explored to utilize the reaction for the synthesis of halogenated and unhalogenated 1, 2, 3-triazines.