Aqueous-Medium Carbon-Carbon Bond-Forming Radical Reactions Catalyzed by Excited Rhodamine B as a Metal-Free Organic Dye under Visible Light Irradiation

作者：Yoshioka Eito; Kohtani Shigeru; Jichu Takahisa; Fukazawa Takuya; Nagai Toyokazu; Kawashima Akira; Takemoto Yoshiji; Miyabe Hideto

来源：Journal of Organic Chemistry, 2016, 81(16): 7217-7229.

DOI：10.1021/acs.joc.6b01102

The utility of rhodamine B as a water-soluble organic photocatalyst was studied in the cascade radical addition-cydization-trapping reactions under visible light irradiation. In the presence of (i-Pr)(2)NEt, the electron transfer from the excited rhodamine B to perfluoroalkyl iodides proceeded smoothly to promote the carbon-carbon bond-forming radical reactions in aqueous media. When i-C3F2I was employed as a radical precursor, the aqueous-medium radical reactions proceeded even in the absence of (i-Pr)(2)NEt. In these reactions, the direct electron transfer from the excited singlet state of rhodamine B would take place. Furthermore, the cleavage of the C-I bond in less reactive i-PrI could be achieved by the reductive electron transfer from the excited rhodamine B, which was confirmed by the fluorescence quenching of rhodamine B with the addition of i-PrI.

• 出版日期2016-8-19