Regioselective Reactions on a Chiral Substrate Controlled by the Configuration of a Chiral Catalyst

A racemic mixture may be partially transformed in the presence of a chiral catalyst by kinetic resolution and formation of products with new structural features. If the starting material is fully consumed the products may still be enantiomerically enriched. The situation is summarized in the Introduction. A brief discussion on the regioselective transformations occurring on a racemic mixture under the influence of a chiral catalyst is presented in Section 2. Often stereo-differences occur, each enantiomer of the starting material resulting in a different product. It allows one to predict what the behaviour of some enantiopure substrates should be in presence of each of the enantiomers of a chiral catalyst. Many examples are presented in Section 3. The chiral substrates under consideration have two different reacting sites, usually of the same nature (OH, C=C, allylic positions, C-H for carbene insertion, epoxide fragment, etc.). In some cases the absolute configuration of the catalyst allows ail excellent control of the regioselectivity. This approach is promising for the selective transformation of chiral molecules.