Diastereo- and enantioselective conjugate addition of α-keto esters to nitroalkenes: Complete switch in the enantioselectivity by tuning the metal center or rigidity of the ligand

Reversal of enantioselectivity in chiral metal complex-catalyzed asymmetric reactions

Asymmetric catalysis represents an efficient approach to prepare optically active compounds. Commonly, both enantiomers of a chiral catalyst are used to synthesize two enantiomers of a chiral compound, however, it is quite difficult to obtain the catalysts with opposite configurations in most cases. Thus, chemists pay much attention to look for new strategies. Enantiodivergent synthesis demonstrates cost effectiveness and practicability to solve this issue by tuning the reaction parameters with the use of ligands derived from a single chiral source. In 2003 and 2008, two reviews have commendably summarized the enantiodivergent reactions, and some representative examples were illustrated. In this review, reversal of enantioselectivity in metal complex-mediated asymmetric catalysis from 2008 to present was updated. Several factors of delivering enantiodivergence are introduced, including metal salts, ligands, additives, solvents, temperature and so on.