DKR Using Hydrolytic Enzymes and Racemization Catalysts

The first reported example of DKR of an amine derives from Reetz et al. in which they employed palladium as a catalyst for the racemization of a methylbenzylamine 1 in the presence of CAL B [37]. The reaction was carried out in pyridine, with ethyl acetate as the acyl donor, at a temperature of 50 55 °C. In order to achieve total conversion to the N acylated product, it was necessary to leave the reaction for 5 days giving the (R) amide in 64% yield and 99% ee. Kim and coworkers extended this approach by employing the in situ reduction of the corresponding oxime 56 to the 

Hult and co workers have reported a modification to the Backvall system in which 1 equiv of isopropyl 2 methoxyacetate was used as the acyl donor in combination with 

---