Catalytic Enantioselective Reactions using Organomanganese Compounds

The use of organomanganese reagents in asymmetric catalysis represents an attractive niche for synthetic chemists mainly due to the toxicological benignancy and low cost.

Yet, the arsenal of the existing organomanganese catalysts, processes and substrates used in the enantioselective reactions is quite limited. This chapter covers the chief achievements made within the last quarter of a century in this area. The majority of the transformations are made by the Mn^III-salen compounds, which are commonly used as potent oxene- and nitrene-transfer agents in the epoxidation and aziridination reactions of CC bonds. The scope, limitations and mechanistic studies of these processes are discussed. Additional class of transformations performed by the Mn^III-salen is asymmetric hydroxylation and amination of CH bonds as well as formation of SO and SN in sulfides. Less common Mn-porphyrin and other scarcely studied complexes and their corresponding asymmetric reactions are discussed as well.

Keywords: Chiral manganese(salen); Jacobsen epoxidation; Katsuki epoxidation; asymmetric sulfoxidation; chiral manganese(porphyrin); asymmetric oxidation; asymmetric amidation