Synthesis
Pyridylboronic pinacol ester (3.64 g, 17.8 mmol), 1,4-dibromobenzene (1.40 g, 5.92 mmol), and Cs2CO3(11.6 g, 35.5 mmol) were added to a 1:1 mixture of dry PhMe/DMF (300 mL), which had been degassed with Ar for 15 min. Next, Pd(PPh3)4(0.68 g, 0.59 mmol) was added to the reaction mixture, and the solution was heated to 130° C. under Ar for 48 h. Then, the reaction mixture was cooled to room temperature, and the palladium catalyst was filtered off using Celite. The organic phase was concentrated under a vacuum and then dissolved, CH2Cl2, followed by extraction with H2O three times. The organic layer was made acidic (pH 2-3) by adding dropwise concentrated HCl, which caused the desired product to precipitate. The precipitate was collected by filtration and then dissolved in H2O. Finally, aq. NaOH (10 M) was added dropwise to the water layer until the pH was 8-9, which resulted in the precipitation of pure product ExBIPY (973 mg, 71 percent) as a white solid.
