Regioselective Halogenation of 6-Azaindoles: Efficient Synthesis of 3-Halo-2,3-disubstituted-6-azaindole Derivatives - Gallou, Fabrice; Reeves, Jonathan T; Tan, Zhulin; Song, Jinhua J; Yee, Nathan K; Campbell, Scot; Jones, Paul-James; Senanayake, Chris H (Synlett, 2005)