CuI-Mediated Sequential Iodination/Cycloetherification of <i>o</i>‑Arylphenols: Synthesis of 2- or 4‑Iododibenzofurans and Mechanistic Studies

An efficient synthesis of 2- or 4-iododibenzofurans through CuI-mediated sequential iodination/cycloetherification of two aromatic C–H bonds in <i>o</i>-arylphenols has been developed. Both the preexisting electron-withdrawing groups (NO<sub>2</sub>, CN, and CHO) and the newly introduced iodide are readily modified for a focused dibenzofuran library synthesis. Mechanistic studies and DFT calculations suggest that a Cu(III)-mediated rate-limiting C–H activation step is involved in cycloetherification.