bromination with POBr3 POCl3

usual condition use Phosphorus(V) oxybromide or Phosphorus(V) oxychloride
in toluene, xylene and heat to over 120 C.
during the rxn, HBr/Br2 can be generated.
sometimes bring side reactions and low yields.

the following paper has a better procedure:
J. Chem. Soc., Perkin Trans. 1, 2002, 529–532

The use of phosphorus oxychloride to prepare compound 12 was sometime fraught with side reactions. Although a very efficient procedure has been recently reported,16 we developed a robust method, also using phosphorus oxychloride or bromide, but in the presence of potassium carbonate in boiling acetonitrile. Thus the troublesome hydrolysis of the reaction mixture takes
place under neutral conditions, without heat evolution, and avoids unwanted decomposition. The 1-halogenated derivatives 13 or 14 were thus routinely prepared in 82–85% yields.