Sequential Nucleophilic Substitution of the [alpha]-Pyrrole and p-Aryl Positions of meso-Pentafluorophenyl-Substituted BODIPYs

Boron-dipyrrins (BODIPYs) have found widespread application in bioimaging and materials science. These applications require the tuning of the chemical and photophysical properties of the fluorophore through the introduction of functional groups at the BODIPY core. In this context, an approach to difunctionalized BODIPYs was explored. Oxidative nucleophilic substitution of hydrogen (ONSH) in the 3-([alpha]-)position of the BODIPYs was combined with nucleophilic substitution (SNAr) at the aryl unit of pentafluorophenyl-substituted BODIPYs and their dipyrrane precursors. In an alternative approach, [alpha]-alkoxy-substituted BODIPYs were prepared starting from the corresponding dipyrrin. In this case, the [alpha]-methoxy group of the BODIPY was susceptible to a hitherto unreported methoxy/amino exchange. The compounds were investigated with respect to their optical spectroscopic properties, revealing the influence of the different substitution patterns on their absorption and emission spectra.