Visible-Light-Induced Construction Of Indole Skeleton And Its Functionalizations

Indoles were very important nitrogenous heterocyclic compound,moreover,the indole moiety as a key building block was widely found in natural products and drugs,with active biological activity and extensive applications.Therefore,its synthesis method has been attracting the attention of chemists.In the past few years,visible light catalysis has made a great breakthrough in the field of organic chemistry.Recently,visiblelight-irradiated organic transformations in the absence of photocatalyst has received considerable attention,providing the further research of photochemistry.In this paper,we mainly focus on the study of visible-light-induced construction of indole skeleton and its functionalizations,and the related research work was carried out as following:1.A novel oxidative cyclization of 2-alkynylanilines with disulfides(diselenides)to3-sulfenyl-and 3-selenylindoles induced by visible-light irradiation in the presence of H2O2 under mild reaction conditions in one pot was developed.The reactions underwent smoothly to generate the desired products in good yields with good functional group compatibility under transition metal-and photocatalyst-free conditions.Compared with the traditional synthesis method,the system is simple and environmental-friendly.2.A convenient and efficient method for the preparation of 3-acylindoles through visible-light-promoted C3-acylation of free(NH)-and N-substituted indoles withα-oxocarboxylic acids under mild reaction conditions was reported.Comparing with the existing procedures for the synthesis of 3-acylindoles,this protocol has several advantages,such as the use of an inexpensive,and easily degradable organic-dye rose bengal as a photocatalyst;ethanol as a low toxicity solvent;and high regioselectivity and good functional group compatibility.