HNTf₂‑Catalyzed Synthesis of Hydrodibenzofurans by an Epoxidation/Semipinacol Rearrangement Cascade

Described here is a highly efficient synthesis of hydrodibenzofurans, an important structural unit lacking general access, in particular, with contiguous quaternary stereocenters. In the presence of HNTf₂ as the superior catalyst and mCPBA as an oxidant, the readily available styrene substrates underwent a one-pot cascade process comprising epoxidation, semipinacol rearrangement, and hemiketal formation to furnish hydrodibenzofurans with good efficiency and diastereoselectivity.