Photoredox Catalysis Induced C-N/C-O Coupling And Cyanation Reactions

The main skeleton of organic molecules is always constructed by C-C bonds,however the function is largely determined by the heteroatoms that contains in.At least one C-N or C-O bonds we can find in almost all the pharmaceuticals,agrochemicals,nature products,and materials,and the formation of these bonds are always the key steps in the construction of these molecules.Though tremendous efforts have been made in this area,the practical generation of C-N and C-O bonds under very mild conditions is still very attractive to all the organic chemists.In this dissertation we reviewed the background of synthetic methods for efficient C-N/C-O coupling,the main work of this dissertation is divided into four parts:(1)heterogeneous photoredox/nickel dual catalysis for C-.N and C-O coupling reactions;(2)indole synthesis via visible-light-driven aza-ortho-quinone methide generation;(3)C-O cross dehydrogenative coupling;and(4)photoredox/nickel dual catalysis for cyanation of aryl halides.First,with the joint use of inexpensive and bench-stable semiconductor CdS and nickel salts,together with mild reaction conditions,we accomplished the efficient C-N and C-O coupling reactions of aryl halrdes with amines and alcohols,makes these two transformations attractive for the synthetic community.This heterogeneous dual catalysis system also proved to be successful in the ligand-free catalytic hydroxylation of aryl bromide with water as a nucleophile.The practicality of this protocol is further emphasized by the scaled-up reaction and the reusability of heterogeneous photocatalysts.Subsequently,we studied the in-situ generation of aza-ortho-quinone methide under visible light induced condition,and accomplished the construction of densely functionalized indoles in a single-flask operation from 2-vinylanilines,halides,and sulfur ylides.In addition,we proposed a possible mechanism with the help of EPR detection,UV-Vis spectrum and DFT calculation.Next,we successfully integrated the cross dehydrogenative coupling process with CO2 reduction under photoredox catalysis condition.The coupling of alcohols and THF α C(sp3)-H was achieved by employing molybdenum oxide and iridium complex.This process is combined with the reduction of CO2,which acts as the oxidant,and delivers formic acid as the side product.This method benefits the cost-effective CO2 reduction and solar-to-fuel conversion.Finally,we applied the dual photoredox/nickel catalysis system into the cyanation of aryl halides,by a detailed screen of cyanation reagents,we developed a practical and safe method for the aryl and vinyl nitriles synthesis.And with the help of DFT calculation,we proposed the detailed mechanism of this transformation.