Enantioselective Conjugate Addition Reactions
via Enamine Activation
Primary and secondary amines can catalyze the conjugate addition reaction of aldehydes and/or ketones to electron-deficient olefins via reversible formation of an enamine intermediate. This reactivity profile together with the possibility of introducing chiral information in different places of the catalyst structure has led to the development of many different methodologies for carrying out enantioselective Michael reactions applying this enamine activation concept. In addition, the application of this manifold to differently functionalized Michael acceptors (nitroalkenes, enones, vinylsulfones, etc.) increases the potential of this methodological approach for application as a very efficient tool for the synthetic organic chemist. In this chapter, the enamine activation concept applied to the Michael reaction will be disclosed and next, a systematic presentation of the different methodologies developed by several research groups can be found which has been organized according to the nature of the Michael acceptor employed.