The iodocarbocyclization of 4-pentenylmalonate I having a substituent at the 2 or 3 position effectively proceeded by treating I with I-2 and Ti(OtBu)(4) in the presence of CuO. Stereoelectronic effect of the subtituent at allylic position on diastereoselectivity was notable. As an application of the present reaction, the efficient synthesis of cyclosarkomycin 7 was achieved.