Functionalization of boron dipyrrin (BODIPY) dyes through iridium and rhodium catalysis: a complementary approach to alpha- and beta-substituted BODIPYs.
Iridium-catalyzed direct borylation has been applied to meso-substituted dipyrromethane and boron dipyrrin (BODIPY) dyes. Borylation is highly regioselective and complementary: it occurs exclusively at the alpha position for meso-mesityldipyrromethane and at the beta positions for meso-mesityl BODIPY dye. This regioselective borylation enables a variety of alpha- and beta-substituted BODIPY dyes to be synthesized. Introduction of alpha,beta-enoate and alpha,beta,gamma,delta-dienoate functions into BODIPY dyes at the alpha or beta positions was achieved by rhodium-catalyzed Heck-type addition of the borylated compounds to acrylate and 2,4-pentadienoate esters. This functionalization has a significant effect on the electronic properties of BODIPY dyes, as seen in substantial redshift of the absorption and emission spectra. Comparative studies showed that the alpha- and beta-substituted series of BODIPY dyes show substantially different photophysical properties, and thus the importance of the position to be functionalized is highlighted.
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Jinping
J
Chen
Masatoshi
M
Mizumura
Hiroshi
H
Shinokubo
Atsuhiro
A
Osuka