Studies Toward Visible Light Induced Regioselective Arylation Of Indole Compound

The arylated indole skeleton is ubiquitous in pharmaceuticals and functional materials,thus their green and efficient synthesis has attracted extensive research interest around the synthetic community.Notably,the regioselective arylation of indoles is one of the most straightforward methods for the rapid access of this functional scaffold.Therefore,the development of step-economic arylation reaction methodologies is highly desirable,albeit challenging regioselective control.In this thesis,we have realized the C2 and N arylation reactions of indole,respectively,using visible light induced radical addition reactions,including the principally regioselective addition of an aryl radicals to indole substrates and nitrogen radicals to aromatic heterocyclic via the proton coupled-electron transfer process.The main contents are detailed in the following two parts:In the first part,the C2 heteroarylation of indole was realized under mild conditions with 2-iodo-5-trifluoromethylpyridine and N-Boc-3-methylindole as model substrate under visible-light irradiation without external photocatalyst.This strategy is featured with high step-economy and good functional group tolerance,in where up to most substrates could achieve excellent reaction efficiency.We also design certain mechanistic experiments for a reasonable reaction process.In the second part,we mainly study photocatalytic N arylation using transition metal complex as photocatalyst.The proton-coupled electron transfer process is proposed for the N-selective arylation with 4-cyanopyridine and 3-methylindole as model substrates under ambient conditions.Further investigation of the substrate scope is still on the way.