Iminium catalysis pericyclic reactions

Iminium catalysis directly utilizes the higher reactivity of the iminium ion in comparison to the carbonyl species and facilitates Knoevenagel-type condensations, cyclo- and nucleophilic additions, and cleavage of cr-bonds adjacent to the a-carbon. Enamine catalysis on the other hand involves catalytically generated enamine intermediates that are formed via deprotonation of an iminium ion, and react with various electrophiles or undergo pericyclic reactions. ... [Pg.16]

Enamine catalysis involves a catalytically generated enamine intermediate that is formed via deprotonation of an iminium ion and that reacts with various electrophiles or undergoes pericyclic reactions. The first example of asymmetric enamine catalysis is the Hajos-Parrish-Eder-... [Pg.4]

The in situ generation of an iminium ion from a carbonyl compound lowers the LUMO energy of the system. Iminium catalysis is comparable to Brpnsted- or Lewis acid activation of carbonyl compounds. The LUMO energy is lowered, the a-CH acidity increases, and nucleophilic additions including conjugate additions as well as pericyclic reactions are facilitated (Eq. 34). [Pg.23]

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