Premium
Functionalization of Boron Dipyrrin (BODIPY) Dyes through Iridium and Rhodium Catalysis: A Complementary Approach to α‐ and β‐Substituted BODIPYs
Author(s) -
Chen Jinping,
Mizumura Masatoshi,
Shinokubo Hiroshi,
Osuka Atsuhiro
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802541
Subject(s) - bodipy , borylation , regioselectivity , chemistry , rhodium , iridium , photochemistry , catalysis , combinatorial chemistry , boron , fluorescence , organic chemistry , aryl , alkyl , physics , quantum mechanics
Abstract Two series of BODIPY dyes with substituents either in the α positions or in the β positions and different conjugation lengths were synthesized by means of iridium‐catalyzed borylation and rhodium‐catalyzed Heck‐type addition (see scheme). The α‐ and β‐substituted series show completely different photophysical properties. BODIPY=boron dipyrrin.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 α position for meso ‐mesityldipyrromethane and at the β positions for meso ‐mesityl BODIPY dye. This regioselective borylation enables a variety of α‐ and β‐substituted BODIPY dyes to be synthesized. Introduction of α,β‐enoate and α,β,γ,δ‐dienoate functions into BODIPY dyes at the α or β 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 α‐ and β‐substituted series of BODIPY dyes show substantially different photophysical properties, and thus the importance of the position to be functionalized is highlighted.