Research on Visible Light Induced Difuctionalization of Alkenes and Alkynes

Author:Gao Fei

Supervisor:xia wu jiong


Degree Year:2017





Visible-light induced organic reactions have gained much interest from chemists,due to their unique properties,such as simple operation,less environmental pollution and less energy consumption.Since alkenes and alkynes are inexpensive and able to participate in many functional reactions,they are widely used in organic synthesis.1,2-difunctionalization of alkenes or alkynes play an important role in the synthesis of natural products,medicine and organic material,because different functional groups can be simultaneously introduced to the double bond or the triple bond.Notably,owing to mild reaction conditions and high selectivity,visible-light-driven 1,2-difunctionalization of alkenes or alkynes has received considerable attention.In this thesis,a series of alkene and alkyne derivatives were synthesized,and visible-light-driven their 1,2-difunctionalizations were studied to synthesize a variety of quinolinones,cyclopenta[c]quinolines,benzo[j]phenanthridines and 3-acyl heteroaromatic compounds.Compounds containing CF3 group have important medical values and practical values.Herein,a visible-light promoted trifluoromethylation of N-arylcinnamamides was reported.This approach,with Togni’s reagent as oxidant and fac-Ir(ppy)3 as photocatalysis,provides a novel access to synthesize varieties of CF3-containing quinolinones.It is interesting to note that when the para-position of the aniline ring was substituted with a methoxy or hydroxyl group,a CF3-containing spiro product was obtained.Mechanism studies show that under visible light irradiation,Togni’s reagent as oxidant was reductively quenched to generate a stable CF3 radical,which underwent the radical addition of the double bond and intramolecular cyclization to obtain the corresponding CF3-containing products.Moreover,the substrates with electron-donating or-withdrawing substituents were all competent partners in this reaction,and the desired products can be obtained in 20%-72% yields.Complex polycyclic hydrocarbons,as the important structural motifs,can be found in numerous natural products and drug molecules.An efficient approach via photoredox catalysis was disclosed for the synthesis of cyclopenta[c]quinolines or benzo[j]phenanthridines from 1,7-enynes in the presence of α-bromo diethyl malonate as oxidant.A mechanism was proposed that with the help of visible light and photocatalyst fac-Ir(ppy)3,α-bromo diethyl malonate was reducted to generate the corresponding radical intermediate.Then,through radical-triggered tandem additions,the bicyclic products were obtained.Most importantly,this method was featured in up to 95% yield,excellent functional group tolerance and operational simplicity.Moreover,the bicyclic structure can be constructed in one step,which may be of great significance to the preparation of polycyclic compounds.Carboxylic acid derivatives are widely used in organic syntheses as readily available and inexpensive basic chemicals.Utilizing air as oxidant,a photocatalytic process for the easy access to carbonylated heteroaromatic compounds has been established via decarboxylation/ cycloaddition/carbonylation.It is worth noting that when α-amino acid derivatives were employed,the desired product can be obtained in absence of the photocatalyst.However,when phenoxyacetic acids or(phenylthio)acetic acid derivatives were employed,the reactions did not proceed in the absence of either photocatalyst or light.In addition,the oxygen atom of the ketonic carbonyl group originates from air,which averted the use of CO as well as resulted waste.