Halogenated organic compounds are versatile building blocks in preparative organic chemistry, with application in syntheses of natural products and preparations of functional materials.1 In addition, a considerable number of halofunctionalized compounds are active pharmaceutical ingredients or important substances in diagnostic medicine.2 Therefore, the development of greener methods for the halogenation of organic substances may be considered a relevant topic in preparative organic chemistry. In this context, inspired by an iodofunctionalization reaction developed in our research group,3 we are exploring the bromofunctionalization of aromatic and heteroaromatic compounds (1) employing NaBr as bromine source, H2O2 (30%) as oxidant, and SeCl4 as catalyst, in water without a co-solvent, which allowed the formation of brominated aromatic and heteroaromatic compounds (2) in yields from 51% to 98% (Table 1).
The scope of the biomimetic bromination reaction presented in Table 1 is being evaluated. Aside from brominated pyrazoles (2k-n), we intend to obtain other brominated heteroaromatic compounds.
1 Hering, T.; Mühldolf, B.; Wolf, R.; König, B. Angew. Chem., Int. Ed. 2016, 55, 5342-5345.
2 Tu, H.; Zhu, S.; Qing, F.-L.; Chu, L. Tetrahedron Lett. 2018, 59, 173-179.
3 Rocha, B. C. O; Perecim, G. P.; Raminelli, C. SynOpen 2019, 3, 142-147.