Bromoindirubins: the synthesis and properties of minor components of Tyrian purple and the composition of the colorant from Nucella lapillus
HPLC-PDA analysis of brominated indirubinoid, indigoid, and isatinoid dyes, Koren ZC
Tanoue Yasuhiro, Ikoma Yousuke, Kai Norihisa, Nagai Takeshi.
Synthesis of halogenoindirubins
Journal of Heterocyclic Chemistry, 2009