Dianionic Oxy‐Cope Rearrangement with Benzil Derivatives: meso‐Selective 3,3‐Coupling of Two Tetrahydrofuran Moieties

Benzil and its derivatives naphthil and pyridil have been found to undergo a dianionic oxy‐Cope rearrangement upon reaction with 2‐lithio‐4,5‐dihydrofuran to give 3,3′‐octahydrobifuranyls selectively as the meso diastereomers. The diastereoselectivity is explained based on the reaction mechanism and the conformation of the starting material. 4,4′‐Di‐tert‐butylbenzil gave the respective intramolecular aldol adduct, whose relative configuration was determined by NOE experiments. The addition of 2‐lithio‐4,5‐dihydrofuran to diaryldiones results in a dianionic oxy‐Cope rearrangement under mild reaction conditions to give 3,3′‐coupled tetrahydrofurans as the meso diastereomers.