Preparation Of BODIPY Derivatives And Their Photocatalytic Performance For The Synthesis Of 2-aryl Benzothiazoles

Boron-dipyrromethene(BODIPY)fuorophores has been proved to be a new type of fluorescent dye for their excellent properties.They are widely used as fluorescen labels,biomoleculer sensors and near IR fluorescent dyes,and they are also applied in biological cell imaging and photodynamics therapy.Meanwhile,due to their unique physical and chemical stabilities,some rearserchers has found BODIPY could play an important role in the field of photocatalytic oxidation.On the basis of a large amount of research literature,we synthesized 5 BODIPY compounds with simple structure.Then we further synthesized 4 BODIPY derivatives by using copper(II)bromide as bromination reagents.The BODIPY 6-9 has a longer wavelength absorption and emission compare with the BODIPY 1-5 by a minor modification.Their structures are confirmed by the 1H NMR,13C NMR and MS spectra and UV-vis absorption and fluorescence spectra of BODIPYs were studied in different solvents.One-pot synthesis of 2-aryl benzothiazoles via BODIPY photocatalyzed oxidation of amines with 2-aminothiophenol in visible light was explored.We are aimed at accomplishing the transformation effectively under a mild condition with non-metal catalyst.A number of experiments were carried out to explore the optimized reaction conditions of the oxidation of benzylamine.The experimental results showed that catalytic activity of BODIPY 7 and BODIPY 9 is significantly better than others BODIPY.We further studied the influence of solvent,temperature and pressure to the oxidative reaction.Finally we decided to set heating the benzylamine and 2-aminothiophenol at 60 ? in the presence of BODIPY 9 irradiated by a 35 W xenon lamp as our optimized condition.With the optimized protocol results in hand,a number of experiments were carried out to explore the scope and limitation of the reaction.We found that the reaction worked very well for a wide variety of substituted benzylamines,obtaining the expected substituted benzothiazoles in yields ranging from 42 to 83%.We also found that oxidation of the electron-donating groups proceeded more efficiently than the electron-withdrawing groups.A simple mechanism was proposed.It is difficult to recycle and reuse BODIPY in the catalytic oxidation.To solve the problem,a BODIPY polymer was prepared to explore the catalytic performance and reused performance.The results show that the BODIPY polymer also presents a high catalytic activity and easy to recycle.