The emerging field of photoredox catalysis offers new ways to facilitate radical reactions under mild conditions by utilizing catalysts that are nontoxic alternatives to radical promoting reagents. Carbazoles, which are nitrogen-containing heterocycles, have potential application as photoredox catalysts. Carbazoles are easily derivitized, metal-free, and have high excited state reduction potentials and high oxidation potential for the regeneration of the catalyst compared to other commercial catalyst equivalents. To avoid the use of high powered mercury lamps, carbazole derivatives with increased conjugation were prepared so that the longer wavelengths of light could excite the catalyst. Currently, the carbazole derivatives with increased conjugation are demonstrated to work well in the dehalogenation of bromobenzenes in catalytic quantities using 365 nm irradiation. One carbazole derivativecontaining two 4-methoxyphenyl groups in 3 and 6 positions has successfully converted 4-bromobenzonitrile to benzonitrile in 78% yield with triethylamine as the hydrogen donor. Future plans include expanding the use of carbazoles as photocatalysts to other redox reactions that could benefit from its unique properties.

Carbazole derivatives as photocatalysts for the dehalogenation of substituted benzenes

2019 Spring National Meeting

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