Asymmetric sulfinyl transfer reactions

Asymmetric sulfinyl transfer reactions are of significant interest, since they can be applied to the synthesis of chiral sulfur-containing compounds, which are valuable synthons for pharmaceuticals and natural products [46]. Moreover, chiral sulfoxides are versatile chiral auxiliaries for asymmetric organic synthesis. A number of studies... 

A recently reported novel asymmetric aziridination route involves the action of methylene transfer reagents on chiral sulfinimines 97, whereby the selectivity is conferred by the asymmetric sulfinyl center. The stereochemical outcome of this reaction is dependent upon the methylene transfer reagent. Thus, dimethyloxosulfonium methylide provided predominantly isomer 98, whereas the use of dimethylsulfonium methylide led to the formation of 99 as the major product [95TL295]. 

An asymmetric variant of this kind of allylic amination, based on their phenylcyclohexanol-derived chiral N-sulfinyl carbamates, was developed by Whitesell et al. (see also Sect. 3.2) (Scheme 34) [85]. After the asymmetric ene reaction with Z-configured olefins (not shown) had occurred, nearly di-astereomerically pure sulfinamides 127 were obtained which were found to be prone to epimerization. Their rapid conversion via O silylation and [2,3]-a rearrangement dehvered the carbamoylated allyhc amines 128 with around 7 1 diastereoselectivity as crystalline compounds that can be recrystallized to enhance their isomeric purity to 95 5. Obviously the imiform absolute configuration at Cl in the ene products 127 was difficult to transfer completely due to the already mentioned ease of epimerization. Unhke the sulfonamides of Delerit (Scheme 33) [84], the carbonyl moiety can easily be cleaved by base treatment. 

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