Asymmetric cyclization of substituted 4-pentenals (Ia,b,c; IIa,b,c,d) by Rh(I) with chiral ligands was tested, and substrate (IId) with a bulkier substituent at C4 underwent more stereoselective cyclization by Rh(I)-((+)-DIPMC) to yield substituted cyclepentanone (IIID). The Rh(I) with (+)-DIPMC was found to proceed in a different manner from the Wilkinson-catalyzed cyclization.