EtAlCl2-induced cyclization of chiral γ,δ-unsaturated ketones 11c and 17b takes place mainly from theexpected face. The selectivity is modest for 11c (60:40) inwhich the large substituent is a primary alkyl group andthe medium substituent is a methyl group and excellent for17b (93:7) in which the large substituent is a cyclohexylgroup and the medium substituent is a methyl group. Thecyclization of 17a is anomalous, suggesting that the phenylgroup has more than a simple steric effect.