Over the past decade, much effort has been put on designing efficient chiral ligands and screening of the different parameters that govern the main challenges of asymmetric S N 2Ј reactions, namely chemo-, regio-and enantioselectivity. This review traces the evolution of the methodologies for creating

The design of chiral ligands is the key to attaining high asymmetric induction in transition-metal-catalyzed reactions. Subtle changes in the conformational, steric, and/or electronic properties of the chiral ligand can often lead to dramatic variation of the reactivity and enantioselectivity. As a result of strong substrate dependence in most cases, tunable and readily synthesized ligands are desirable to obtain high enantioselectivities.Nowadays, asymmetric copper-catalyzed conjugate addition and allylic substitution are well-developed methodologies for creating CÀC bonds. Many efforts have been made in designing efficient systems and identifying new ligands to improve enantioselectivities.

We describe herein the development of the first iridium-catalyzed allylic substitution using arylzinc nucleophiles. High enantioselectivities were obtained from the reactions, which used commercially available Grignard reagents as the starting materials. This methodology was also shown to be compatible with halogen/metal exchange reactions. Its synthetic potential is demonstrated by its application towards the formal synthesis of (+)-sertraline.

The design of chiral ligands is the key to attaining high asymmetric induction in transition-metal-catalyzed reactions. Subtle changes in the conformational, steric, and/or electronic properties of the chiral ligand can often lead to dramatic variation of the reactivity and enantioselectivity. As a result of strong substrate dependence in most cases, tunable and readily synthesized ligands are desirable to obtain high enantioselectivities.Nowadays, asymmetric copper-catalyzed conjugate addition and allylic substitution are well-developed methodologies for creating CÀC bonds. Many efforts have been made in designing efficient systems and identifying new ligands to improve enantioselectivities.

[reaction: see text] Phosphoramidites based on BINOL readily react with trimethylaluminum in "noncoordinating" solvents, leading to the corresponding aminophosphine which is the real ligand in copper-catalyzed asymmetric transformations. This artifact explains the experimental differences in the asymmetric ring opening of meso bicyclic hydrazines using dialkylzinc or trialkylaluminum reagents as nucleophiles.