Fig. 2. Ring-closing C–O/C–O σ-bond metathesis of ethers with alcohols.

^aReaction conditions: reactions were performed with 1 (1.0 equiv.), solvent (0.2 M), catalyst (2 mol%) at 100 °C for 12 h, isolated yields were provided unless mentioned otherwise. ^b3 mol% Re₂O₇, 120 °C, 24 h. ^cYields were determined by analyzing ¹H NMR of the reaction mixture with an internal standard. ^d4 mol% Re₂O₇, 120 °C, 24 h. ^e5 mol% Re₂O₇, 120 °C, 24 h. ^f2 mol% Re₂O₇, 80 °C, 12 h.