Abstract A range of substituted propargyl alcohols form ethers with allyl bromide in good yields; conversion of these ethers to the alkyne hexacarbonyl dicobalt complexes using Co 2 (CO) 8, followed by intramolecular cyclisation gives substituted 3-oxabicyclo [3.3. 0] oct-6-en- 7-ones (4a–4e) in fair to moderate yields.