Cyclic enol ether synthesis via arenesulfonyl iodide additions to alkynols

Article abstract of DOI:10.1016/S0040-4020(96)00346-8

The reaction of arenesulfonyl iodides with alkynols generally provides adducts in good yields. Treatment of these adducts with KN(SiMc₃)₂ gives enol ethers; cyclisation of the functionalised pentenol (5) results in formation of the exo-alkylidene tetrahydrofuran (7), whereas the homologous hexenol (6) gives the dihydropyran (8). Attempts to cyclise the hexenol (6) with potassium t-butoxide under the conditions reported by Short and Ziegler generally gave the endocyclic ether (8).