Reaction of cyclic 8-aryl-2-en-7-yn-1-ones with iron(III) chloride affording (E)-spiro[4,5]decanone derivatives was developed. Treatment of 1.5 eq of FeCl3 with cyclic 8-aryl-2-en-7-yn-1-ones in 1,2-dibromoethane at 45 ℃ for 2-16 hours produced (E)-spiro[5,4] decanone derivatives in 20-50 %. Iron(III) chloride was also an excellent Lewis acid to promote the synthesis of (E)-spiro[4,5]decene systems from cyclic 8-aryl-2-en-7-yn-1-ols. The reaction occurred in less than 3 minutes at room temperture in methylene chloride solution and in good yields.