The diastereoselectivity in the conjugate addition of organocopper reagents to γ-aryl α, β- unsaturated carbonyl derivatives 8–14 was investigated. The syn-diastereoselectivity was obtained irrespective of the reagents type in the addition of 8, while the anti- diastereoselectivity was obtained in the addition of 10–14 with RCu and RCu (CN) Li (R= Me and Bu) and the syn-selectivity was produced in the addition of 10–14 with R2CuLi ...