Water in Stereoselective Organocatalytic Reactions

In this review, recent advances in asymmetric organocatalytic reactions carried out with variable amounts of water, from substoichiometric to a large excess (reaction medium), are discussed. We also summarize several proposed mechanisms for the different possibilities of the action of water both in the increased activity of the catalyst and in the asymmetric induction. Finally, the application of this catalytic methodology to the enantioselective synthesis of valuable compounds through enamine or iminium catalysis is presented. 1 Introduction 2 Aldol Reactions 2.1 Primary Amino Acids as Catalysts 2.2 Proline 2.3 Prolines Substituted in the 4-Position 2.4 Prolinamides 2.5 Dipeptides and Small Peptides as Catalyst 2.6 Pyrrolidine-Based Derivatives 2.7 Miscellaneous 3 Michael Reactions 4 Mannich Reactions 5 Diels-Alder Reactions 6 Conclusions