Beta-iodoallenolates II, generated from alkynones I with tetra-n-butylammonium iodide and a Lewis acid, underwent selective single or double annulation, depending on the Lewis acid promoter. Treatment with TiCl(4) gave cyclohexenyl alcohols III, whereas BF(3) x OEt(2) gave oxadecalins IV. The scope and limitations of the two annulation reactions are described.
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