Visible-Light-Induced Free Radical Reactions To Synthesize Diarylmethanes/Difluoromethyl-Containing Isoquinoline-1,3-Diones

Visible-light-induced organic reactions have shown important application values and broad industrialization prospects in organic synthesis due to their advantages of high efficiency,mild reaction condition and green reaction.The cheap and easily available photocatalysts-induced free radical reactions provides a new strategy for the construction of complex compound frameworks and is becoming a frontier field in organic chemistry research.The organic dye catalysts used in this work have the advantages of being cheaper and non-toxic compared with the commonly used metal photocatalysts such as ruthenium（II）and iridium（III）,what’s more,they have wider absorption ranges and are therefore more attractive for photo-redox reactions.In this thesis,we focused on the following two parts of cheap organic dye catalyzed and visible-light-induced free radical tadem reactions:1)visible-light-induced free radical reactions to synthesize diarylmethane compounds;2)visible-light-catalyzed free radical reactions to synthesize difluoromethyl-containing isoquinoline-1,3-dione compounds.Diarylmethanes are significant frameworks of biologically relevant molecules and pillar arenes.Furthermore,they can be also used in the preparation of electroactive and photoactive oligomers and polymers.On account of the importance of these chemicals,various methods for their synthesis have been developed.This molecular scaffold has mostly been accessed through Friedel-Crafts alkylation or transition-metals-catalyzed cross-coupling reactions.However,these methods still suffer from the disadvantages of metal residues and severe reaction conditions.Here,an efficient method by using visible-light-induced and transition-metal-free catalytic radical reactions for synthesis of diarylmethanes with N,N-dimethylaniline was developed.The innovation of thesis is that the formation of key methylene by cheap and readily available N,N-dimethylaniline via substrate self-oxidation,molecular addition,C-N bond cleavage.This method avoids additional methylene unit,metal residues and severe reaction conditions.The control experiments illustrated that the diarylmethanes formed from radical addtions,mult-steps oxidation,deprotonation and C-N cleavage.Isoquinoline-1,3-diketone derivatives are important organic compounds and have important drug activities.Fluorine-containing groups have strong electron absorption and high lipophilicity.The introduction of fluorine-containing groups into bioactive compounds can effectively modify cell membrane permeability and improve bioavailability.Therefore,the introduction of fluorine-containing groups into isoquinoline-1,3-diones is very important.In here,a novel visible-light-induced and air-promoted direct radical difluoromethylation of N-benzamides for synthesis of CF₂H-containing isoquinoline-1,3-diones has been achieved,which represents the first metal-free catalytic synthesis of CF₂H-containing isoquinoline-1,3-diones.This protocol provides an efficient strategy for the synthesis of a variety of CF₂H-containing isoquinoline-1,3-diones with commercially available Na SO₂CF₂H.The reaction features mild reaction conditions,metal-free,air oxidation and additives free,as well as has the advantages of atomic economy and step economy.The control experiments showed that:the excited Eosin B*is formed under irradiation,and then an electron transfers from Na SO₂CF₂H to Eosin B*to generate a highly reactive CF₂H radical.Subsequently,through a radical addition and it undergoes a radical cyclization to provide isoquinoline-1,3-diketone.Furthermore,the transformation of product to important potential against HIV pharmaceutical N-OH substituted isoquinoline-1,3-dione has been successfully realized.