A highly stereoselective synthesis of (m>Zm>)-chloroalkene dipeptide isosteres (CADIs) of the Xaa-Gly type has been achieved. Treatment of an allylic m>gemm>-dichloride with an organocuprate provided (m>Zm>)-chloroalkene formation corresponding to an Xaa-Gly type CADI through reductive dechlorination in high yield with (m>Zm>)-selectivity.