Cyclopropanes Dioxirane

The vast majority of organocatalytic reactions proceeds via covalent formation of the catalyst-substrate adduct to form an activated complex. Amine-based reactions are typical examples, in which amino acids, peptides, alkaloids and synthetic nitrogen-containing molecules are used as chiral catalysts. The main body of reactions includes reactions of the so-called generalized enamine cycle and charge accelerated reactions via the formation of iminium intermediates (see Chapters 2 and 3). Also, Morita-Baylis-Hillman reactions (see Chapter 5), carbene-mediated reactions (see Chapter 9), as well as asymmetric ylide reactions including epoxidation, cyclopropanation, and aziridination (see Chapter 10), and oxidation with the in situ generation of chiral dioxirane or oxaziridine catalysts (see Chapter 12), are typical examples. 

The examples above further demonstrate that dioxirane reactions are characterized by high selectivity and that tert-C-H bonds are considerably more reactive towards dioxirane 0-insertion than their sec-C-H complements. However, the cyclopropane moiety, if suitably oriented, can have a marked influence in activating proximal a-C-H bonds towards dioxirane oxyfunctional-ization. ... 

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