Iodide ion-enabled highly regioselective α-C(sp³)-H triazolization of ethers with N-sulfonyl-1,2,3-triazoles

An efficient iodide ion (I⁻)-enabled method for direct α-C(sp³)-H triazolization of ethers via a radical cross-coupling has been developed for regioselective construction of N²-substituted hemiaminal ethers. The developed C(sp³)-H triazolization reaction features the resulting products in good yields (up to 90%) and an excellent functional group tolerance to various ethers, including cyclic and linear ethers. Preliminary mechanistic study and DFT calculation investigation indicate that the reaction proceeds via a S_N2-like desulfonylation radical coupling process and an (I⁻)-involved ternary complex is responsible for the high conversion ratio and the high regioselectivity. I⁻ not only promotes the process but also prevents the in situ generated carbon-centered radicals (CCRs) from being oxidized into carbon cations in an oxidative environment.