Treatment of allenyl-aldehyde dimethyl acetals with iodotrimethylsilane, titanium tetrachloride, and indium trichloride afforded a mixture of separable cis- and trans-2-haloalkenyl substituted 2-haloalkenylcycloalkyl methyl ethers by intramolecular nucleophilic attack of allene moiety to the oxonium ion generated by the reaction of TMSI, TiCl4, or InCl3 to dimethyl acetal moiety. (C) 2002 Elsevier Science Ltd. All rights reserved.