Copper- and Visible-Light-Catalyzed Cascade Radical Cyclization of N-Propargylindoles with Cyclic Ethers.

An efficient visible-light-assisted, copper-catalyzed tandem radical cyclization of N-propargylindoles with cyclic ethers is established. A series of 2-oxoalkyl-9H-pyrrolo[1,2-a]indol-9-ones with potential biological activities were synthesized in moderate yields by using a dual catalytic system with copper acetate as a transition metal catalyst and eosin Y as a visible light catalyst. The investigation of reaction mechanism shows that it goes through a cascade oxoalkyl radical addition, cyclization, and oxidation process.

TsCl-promoted thiolation of quinoline N-oxides with thiophenols.

A metal-free method for the regioselective synthesis of 2-thiolated quinolines from quinoline N-oxides in water at room temperature is developed. The reaction is conducted using benzenethiols as thiolation reagents in the presence of p-toluenesulfonyl chloride via p-toluenesulfonyl chloride-assisted tandem C-H bond activation, nucleophilic addition, deoxygenation and aromatization processes. This method does not require the use of metal catalysts and oxidants. It shows the advantages of wide functional group tolerance, short reaction times and simple operation.