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Regioselective stepwise bromination of boron dipyrromethene (BODIPY) dyes
Lijuan Jiao1, Weidong Pang, Jinyuan Zhou
1Laboratory of Functional Molecular Solids, Ministry of Education, School of Chemistry and Materials Science, Anhui Normal University, Wuhu, Anhui, 241000, China. jiao421@mail.ahnu.edu.cn
Abstract:
Halogenated BODIPYs are important synthetic precursors and potential sensitizers for photodynamic therapy (PDT). Electrophilic bromination of pyrrolic-unsubstituted BODIPYs using bromine regioselectively generated mono- to heptabromoBODIPYs in a stepwise fashion in good to excellent yields. These resultant bromoBODIPYs were applied for regioselective substitution and Suzuki coupling reaction to generate BODIPYs 4, 5, 6, and 7 in good to excellent yields. According to NMR and X-ray analysis results, the stepwise bromination first takes place at 2,6-, then at 3,5-, and eventually at 1,7-positions, whereas the regioselective substitution occurs first at 3,5- then at 1,7-positions of the chromophore. The spectroscopic properties of these resultant BODIPYs were studied, which shows the potential application of these bromoBODIPYs as sensitizers for PDT.
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