Visible Light Induced The Transformation Of Aliphatic Primary And Secondary Amines

Visble light is a green inexhaustible energy.Over the past decade,photocatalysis has been rapidly developed and it was emerged as a valuable tool in organic synthesis.Photoredox-catalyzed can realize many reactions that are difficult to carry out by traditional methods.Besides,Visible light induced organic reactions exhibit some advantage such as mild confition,high reactivity and easy operation.Amines are extremely important structures in organic chemistry.The synthesis of valueable skeleton using of readily available amines as feedstocks is always be one of the hot topics in organic chemistry.In this dissertation,visible light promoted the transformation of aliphatic primary and secondary amines were investigated,and some achievements are obtained as follows:Firstly,visible light induced the conversion of aliphatic primary and secondary amines to 1,4-dicarbonyl compounds has been developed.Using 4CzIPN as photocatalyst,oxygen serving as oxidant,toluene and H2O as mixed solvent,a series of amine compounds and electron-deficient olefins can be efficiently converted into 1,4-dicarbonyl compounds under the irradiation of visible light,the yields of 1,4-dicarbonyl compounds is up to 76%.The direct radical addition of unprotected secondary and primary amines to electrondeficient alkenes has been realized,we provides a new strategy for visible-light-driven C(sp3)-H activation of amines.Moreover,the substrate scope of this method is broad and a wide array of functional groups are tolerated.The mechanism investigations showed that the reaction via a process of the SET oxidation and deprotonation of amines to generate a-aminoalkyl radical,γ-aminocarbonyl compounds generated from the addition of α-aminoalkyl radicals to α,β-unsaturated esters could be oxidized to 1,4-dicarbonyl.Secendly,visible light induced multicomponent radical-radical coupling of primary amines aromatic,aldehydes and 4-cyanopyridine to form pyridinmethanamine was developed.Without photocatalyst,using DMSO as solvent,in the presence of HCOOCs and AcOH,the conversion of amines,aldehydes and 4-cyanopyridines to pyridinmethanamine colud be realized under the irradiation of visible light.A series of primary amines,aromatic aldehydes and 4-cyanopyridines can participate in the reaction,and the reaction yield is up to 83%.The substrate scope of this method is broad and a wide array of functional groups are tolerated including nature procuct,pharmaceutical and amino acid ester.In the absence of amine,the reductive coupling of aromatic aldehyde and 4-cyanopyridine was achieved to obtain pyridinemethanol compounds.Mechanistic studies have shown that carbon dioxide radical anion and excited dimsyl anion could generate from the formate salt-DMSO mediated system under the induction of visible light,and the intermediates can reduce the imine(generated in situ by amines and aldehydes)and cyanopyridine to generate the corresponding radical,and then the target pyridinmethanamine compound is obtained by radical-radical coupling.At last,visible light induced synthesis of ureas and formamides from amines and CO2 has been developed.Using Ir[df(CF3)ppy]2(dtbbpy)PF6 as photocatalyst,Ph3P is the only addctice,readily available amines as feedstocks,CO2 as the C1 source,a range of ureas could be directly accessed under ambient temperature and pressure,the reaction yileds is up to 81%.This work represents a rare example of the synthesis of ureas under ambient temperature and pressure.In addition,Using triisopropylsilanethiol as the hydrogen source,formamides could be produced,the reaction yileds is up to 80%.The mechanism investigations showed that triphenylphosphine or triisopropylsilane thiol can promote dehydration of carbamate anion species(generated in situ by amines and CO2)could give carbamoyl radical.The further transformation can obtain urea or amide compounds.