Pd-Catalyzed Direct C–H Functionalization/Annulation of BODIPYs with Alkynes to Access Unsymmetrical Benzo[b]-Fused BODIPYs: Discovery of Lysosome-Targeted Turn-On Fluorescent Probes

Abstract

A highly efficient palladium-catalyzed direct C-H functionalization/annulation of BODIPYs with alkynes has been developed for the first time to construct a series of unsymmetrical benzo[ b]-fused BODIPYs from readily available starting materials. These unsymmetrical benzo[ b]-fused BODIPYs exhibit remarkably red-shifted emissions and larger Stokes shifts than classical BODIPY dyes. Cell imaging experiments and cytotoxicity assays demonstrate that BODIPYs 4c and 4d have specific lysosome-labeling capacities, turn-on fluorescence emissions in cells, and low cytotoxicity.

Synthesis and Characterization of Boron Difluoride Complexes Bearing π-Expanded Pyridine Ligands as Organic Fluorochromes

“…While the dipyrromethene, the ligand of BODIPY, has a highly symmetric structure derived from dipyrrole, the design of the novel ligands based on the desymmetrization with the expansion of the π-conjugated system could be a powerful approach to achieve unique optical properties. In recent years, various groups have reported the enlarging the Stokes shift of boron complexes by using nonsymmetric ligands such as anilido-imine and pyridine, benzo-fused dipyrromethene, and carbazole­[2,1- c ]­phenanthridine . Moreover, applying ligands with intramolecular charge transfer (ICT) character was often useful for the bathochromic shift of emission bands .…”

Detection of Lysosome by a Fluorescent Heterocycle: Development of Fused Pyrido–Imidazo–Indole Framework via Cu-Catalyzed Tandem N-Arylation

“…IR spectrum of the solid sample was recorded in the range 400 to 4000 cm −1 in a Bruker FT-IR spectrometer. All the 1 H and 13 C NMR spectra were recorded in a Bruker 600 MHz spectrometer. ESI mass spectral analysis was done using LCQ-ORBITRAP-XL instrument.…”

“…In recent times, nitrogen containing heterocycles have gained high importance due to their impactful and versatile applications in various fields. − Thus, researchers are interested in synthesis of these kinds of fused heterocycles. These fused heterocycles due to their extensive conjugations are also highly fluorescent and can be used in bioimaging. − Imidazo­[1,2- a ]­pyridine, one of the most important examples of nitrogen bearing heterocycles, was found to be major constituent of different pharmaceuticals (Figure ). Some of the reported anticancer, antiparasitic, anti-inflammatory, antiviral, and antibacterial drugs consist of the imidazo­[1,2- a ]­pyridine motif.…”

Annulative π-extension of BODIPYs made easy via gold(i)-catalyzed cycloisomerization

“…However, over the last few years, the postfunctionalization of the BODIPY core by annulation has gained increased attention as a new efficient synthetic strategy (Scheme 1b). In this regard, several chemical transformations such as oxidative aromatic coupling, 14 one-pot Suzuki-Miyaura-Knoevenagel reaction 15 or direct C-H palladium catalyzed annulation, 16 have been recently reported to prepare [b]-phenanthro and [b]-naphtho-fused-BODIPYs. However, these methodologies, although elegant, are quite limited in terms of scope, yield, group tolerance and availability of the starting material.…”