Resolution, regiodivergent

Reaction of epichlorhydrin a-Acetoxy sulfide Enzymes and metals together Hydrogenation Parallel Kinetic Resolutions Regiodivergent resolutions Double Methods... 

Scheme 22.10B) were achieved in high selectivity, although a relatively high catalyst loading was required. This method for asymmetric silylation was successfully extended to the regiodivergent resolution of racemic 1,2-diols 50 (Scheme 22.10C). ... 

Pineschi and Feringa reported that chiral copper phosphoramidite catalysts mediate a regiodivergent kinetic resolution (RKR) of cyclic unsaturated epoxides with dialkylzinc reagents, in which epoxide enantiomers are selectively transformed into different regioisomers (allylic and homoallylic alcohols) [90]. The method was also applied to both s-cis and s-trans cyclic allylic epoxides (Schemes 7.45 and 7.46,... 

The identification of a novel BVMO from Mycobacterium tuberculosis (BVMOMtbs) complements this toolbox, as this particular biocatalyst performs a classical kinetic resolution instead of a regiodivergent oxidation vith complete consumption of substrate [140]. Notably, this enzyme accepts only one ketone enantiomer and converts it selectively to the abnormal lactone while the antipodal substrate remains unchanged (Scheme 9.24) [141]. 

Cu(OTf)2 (2mol%) is required (Equation (110)).183 The nature of the copper salt strongly influences the enantio-selectivity, and copper carboxylates proved to be especially efficient (Equation (lll)).184b It has been applied for an enantioselective synthesis of prostaglandin E methyl ester (Equation (112)),185 and can be used for the performance of a highly regiodivergent and catalytic parallel kinetic resolution.186... 

Scheme 2.59 Regiodivergent parallel kinetic resolution of cyclic ketones [114].

The versatility of this approach was demonstrated by applying it to seven different substrates (Scheme 3.17). The corresponding chiral products were obtained in very good to excellent conversions (63-99%) and absolute stereoselectivities (>99%), particularly when regiodivergent oxygenations were in principle possible. Thereby, the major classes of reactions in asymmetric synthesis or racemate resolution were investigated (desymmetrization, kinetic resolution, and regiodivergent trans formations). 

Bertozzi F, Crotti P, Macchia F, Pineschi M, Feringa BL (2001) Highly enantioselective regiodivergent and catalytic parallel kinetic resolution. Angew Chem hit Ed 40 930-932... 

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