Asymmetric Sulfimidation

Armstrong et al. reported the amination of various sulfides with iV-acyloxaziridines <2002CC904, 2003TL5335>. Treatment of various sulfides 87 with 88 in trifluoroethanol afforded sulfimides 89 and sulfoxides 90, with the former predominating (Table 4). Asymmetric sulfimidation with a chiral oxaziridine 92 gave low diastereoselectivities (Equation 2) <2003TL5335>. 

The synthesis of sulfoximides and sulfimides has attracted considerable attention in recent years due to the potential utility of these compounds as efficient auxiliaries and chiral ligands in asymmetric synthesis (reviews [86-88]). Transition metal-catalyzed nitrene transfer to sulfoxides and sulfides is an efficient and straightforward way to synthesize sulfoximides and sulfimides, respectively. Bach and coworkers reported the first iron-catalyzed imination of sulfur compounds with FeCl2 as catalyst and B0CN3 as nitrene source. Various sulfoxides and sulfides were... 

In summary, we have presented a variety of metal-based catalysts which are able to mediate the asymmetric oxidations of sulfides to the corresponding sulfoxides and sulfimides. Although very different approaches relying on distinct metal complexes are known, there is still a demand for an appropriate system which would allow the transformation of any sulfide to occur with high enantioselec-tivity. Especially the rational design of chiral complexes able to selectively oxidize substrates, in particular, those compounds other than aryl methyl sulfides is still a major challenge. 

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