Tuning the Photophysical Properties of Flavins by Attaching an Aryl Moiety via Direct C-C Bond Coupling

Palladium-catalyzed Suzuki reactions of brominated flavin derivatives (5-deazaflavins, alloxazines, and isoalloxazines) with boronic acids or boronic acid esters that occur readily under mild conditions were shown to be an effective tool for the synthesis of a broad range of 7/8-arylflavins. In general, the introduction of an aryl/heteroaryl group by means of a direct C-C bond has been shown to be a promising approach to tuning the photophysical properties of flavin derivatives. The aryl substituents caused a bathochromic shift in the absorption spectra of up to 52 nm and prolonged the fluorescence lifetime by up to 1 order of magnitude. Moreover, arylation of flavin derivatives decreased their ability to generate singlet oxygen.

Automated summary

Palladium-catalyzed Suzuki reactions of brominated flavin derivatives are an effective method for synthesizing a broad range of 7/8-arylflavins. Introducing aryl/heteroaryl groups through direct C-C bond formation can tune the photophysical properties of flavin derivatives, leading to bathochromic shifts in absorption spectra and prolonged fluorescence lifetimes. Additionally, arylation of flavin derivatives reduces their ability to generate singlet oxygen.