Aqueous-Medium Carbon-Carbon Bond-Forming Radical Reactions Catalyzed by Excited Rhodamine B as a Metal-Free Organic Dye under Visible Light Irradiation.
The utility of rhodamine B as a water-soluble organic photocatalyst was studied in the cascade radical addition-cyclization-trapping reactions under visible light irradiation. In the presence of (i-Pr)2NEt, 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-C3F7I was employed as a radical precursor, the aqueous-medium radical reactions proceeded even in the absence of (i-Pr)2NEt. 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.
School of Pharmacy, Hyogo University of Health Sciences , Minatojima, Chuo-ku, Kobe, 650-8530, Japan.
Eito
E
Yoshioka
School of Pharmacy, Hyogo University of Health Sciences , Minatojima, Chuo-ku, Kobe, 650-8530, Japan.
Shigeru
S
Kohtani
School of Pharmacy, Hyogo University of Health Sciences , Minatojima, Chuo-ku, Kobe, 650-8530, Japan.
Takahisa
T
Jichu
School of Pharmacy, Hyogo University of Health Sciences , Minatojima, Chuo-ku, Kobe, 650-8530, Japan.
Takuya
T
Fukazawa
School of Pharmacy, Hyogo University of Health Sciences , Minatojima, Chuo-ku, Kobe, 650-8530, Japan.
Toyokazu
T
Nagai
School of Pharmacy, Hyogo University of Health Sciences , Minatojima, Chuo-ku, Kobe, 650-8530, Japan.
Akira
A
Kawashima
Graduate School of Pharmaceutical Sciences, Kyoto University , Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
Yoshiji
Y
Takemoto
School of Pharmacy, Hyogo University of Health Sciences , Minatojima, Chuo-ku, Kobe, 650-8530, Japan.
Hideto
H
Miyabe