Metal-free Desulfonylation And Aromatization Via Visible Light Photoredox

Photoredox catalysis via visible light can reduce the limitation of substrates and improve the chemoselectivity of photo-reaction, which could utilize solar energy into chemical synthesis directly and become one of highlights in area of organic chemistry recent years. In addition, commercially-available organic dye mediated visible-light photoredox catalysis also draw much attention from chemists. This thesis is about visible light photoredox catalysis:applications in organic synthesis. We developed several useful organic reactions via visible-light photoredox catalysis and studied the mechanism of these reactions via looking for new reaction system of visible-light photoredox catalysis. As below:First, the desulfonylation of β-ketosulfones has been achieved with good to excellent yields under irradiation of3W blue LEDs light by using1mol%organic dye eosin Y bis-(tetrabutylammonium salt) as photocatalyst and diisopropylethylamine as reducing agent. Flash-photolysis study indicates oxidative quenching plays important roles in the photoredox catalytic cycles.Second, the synthesis of pyrimidine, benzoxazole, benzothiazole, parazole and hantzsch ester via aromatization has been finished with good to excellent yields under irradiation of3W blue LEDs light by using1mol%organic dye eosin Y bis-(tetrabutylammonium salt) as photocatalyst and air as oxidizing agent, a base added too. The experiments of electron spin resonance (ESR) indicate the base in the reaction system plays a role of restraining singlet oxygen (’02).