The use of secondary amines as asymmetric catalysts in transformations of carbonyl compounds has seen tremendous development in recent years. Going from sporadic reports of selected reactions, aminocatalysis can now be considered as one of the methods of choice for many asymmetric functionalizations of carbonyl compounds--primarily of aldehydes and ketones. These functionalizations have been published at a breathtaking pace over the last few years--during the "golden age" and "gold rush" of organocatalysis. This tutorial review will firstly sketch the basic developments in organocatalysis, focussing especially on the use of secondary amines as catalysts for the functionalization of aldehydes and alpha,beta-unsaturated aldehydes, with emphasis on the mechanisms of the transformations and, secondly, outline recent trends within central areas of this research topic. Lastly, we will present our guesses as to where new developments might take organocatalysis in the years to come.

A new concept in organocatalysis is presented, the direct asymmetric gamma-functionalization of alpha,beta-unsaturated aldehydes. We disclose that secondary amines can invert the usual reactivity of alpha,beta-unsaturated aldehydes, enabling a direct gamma-amination of the carbonyl compound using azodicarboxylates as the electrophilic nitrogen-source. The scope of the reaction is demonstrated for the enantioselective gamma-amination of different alpha,beta-unsaturated aldehydes, giving the products in moderate to good yields and with high enantioselectivities up to 93% ee. Experimental investigations and DFT calculations indicate that the reaction might proceed as a hetero-Diels-Alder cycloaddition reaction. Such a mechanism can explain the "unexpected" stereochemical outcome of the reaction.

The mechanisms of the α-, β- and γ-functionalisations of aldehydes and α,β-unsaturated aldehydes by secondary amines are presented and discussed.

The development of the organocatalytic asymmetric one-pot Michael-Darzens condensation giving highly functionalized complex epoxycyclohexanone derivatives with up to four chiral centers is presented. Depending on the reaction conditions, either the polysubstituted 7-oxa-bicyclo[4.1.0]heptan-2-one ring system or 2-chloro-cyclohex-2-enone derivatives can be formed. For the former class of compounds a high diversity in substitution pattern is demonstrated, and the optically active products are obtained in excellent diastereo- and enantioselectivities. The potential synthetic applications of the products have been demonstrated by performing a series of highly diastereoselective transformations leading to optically active products useful for the life-science industry. Furthermore, mechanistic investigations on the formation of the chiral centers in the optically active epoxycyclohexanone are presented.