Towards perfect catalytic asymmetric synthesis: Dual activation of the electrophile and the nucleophile

The design and development of new high-performance catalysts for applications in asymmetric catalytic reactions is of ongoing interest in organic chemistry. The combination of a Lewis acid and a Lewis base working in concert is now considered state of the art in stereoselective syntheses. The synergistic activation by two or more reactive centers allows high reaction rates and excellent transfer of stereochemical information. Despite the self-quenching reaction between Lewis acids and Lewis bases that might lead to an inactive catalyst, considerable effort has been directed towards the development of the dual-activation concept. The ultimate goal is to mimic nature by the discovery of catalytic systems analogous to enzymatic processes that involve metal-ion cocatalysts. With this aim, the dual activation concept greatly broadens the range of artificial catalysts. The most efficient catalytic systems are reviewed, and the mechanisms of action are discussed.