Introduction of Ether Groups onto Electron-Deficient Nitrogen-Containing Heteroaromatics Using Radical Chemistry under Transition-Metal-Free Conditions

Electron-deficient nitrogen-containing heteroaromatics, such as quinoline, isoquinoline, and pyridine, were treated with benzoyl peroxide in dioxane, tetrahydropyran, tetrahydrofuran, diethyl ether, and dipropyl ether at 80 °C to form alkylated nitrogen-containing heteroaromatics in good yields under transition-metal-free conditions. This method was successfully applied to the preparation of lariat aza-crown ethers using 18-crown-6 or 15-crown-5 with quinoline and isoquinoline in the presence of benzoyl peroxide in good yields under irradiation conditions with a Hg lamp.