Dynamic Kinetic Resolution of Amines and Amino Acids

3 DYNAMIC KINETIC RESOLUTION OF AMINES AND AMINO ACIDS 

Products from the asymmetric transformation of ketoximes to chiral amides via the DKR of amines. 

5 DYNAMIC KINETIC RESOLUTION OF ALCOHOLS, AMINES, AND AMINO ACIDS 

Products from the DKR of ben-zylic amines with CAL-B and Pd/ BaSO,. 

Asymmetric reductive acetylation of benzylic ketoximes with CAL-B and Pd/AIO(OH). 

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Kim, Y.-W., Park, ).-W., and Kim, M.-J. (2011) Dynamic kinetic resolution of amines and amino acids by enzyme-metal Co-catalysis. ChemCatChem, 3, 271-277. 

Scheme 19.13 Dynamic kinetic resolution of cyclic P-amino acid derivatives based on amine-catalyzed racemization and enzymatic oxazinone hydrolysis.

Dynamic Kinetic Resolution of Alcohols, Amines, and Amino Acids... 

The complete transformation of a racemic mixture into a single enantiomer is one of the challenging goals in asymmetric synthesis. We have developed metal-enzyme combinations for the dynamic kinetic resolution (DKR) of racemic primary amines. This procedure employs a heterogeneous palladium catalyst, Pd/A10(0H), as the racemization catalyst, Candida antarctica lipase B immobilized on acrylic resin (CAL-B) as the resolution catalyst and ethyl acetate or methoxymethylacetate as the acyl donor. Benzylic and aliphatic primary amines and one amino acid amide have been efficiently resolved with good yields (85—99 %) and high optical purities (97—99 %). The racemization catalyst was recyclable and could be reused for the DKR without activity loss at least 10 times. 

List and coworkers reported an excellent approach to the enantioselective synthesis of P branched a amino phosphonates, which involved the extension of the dynamic kinetic resolution strategy (Scheme 3.53) [110] that was previously applied to the enantioselective reductive amination of a branched aldehydes by his research group (see Scheme 3.45). The method combines dynamic kinetic resolution with the parallel creation of an additional stereogenic center. They successfully accomplished the direct three component Kabachnik Fields reaction of 1 equiv each of the racemic aldehyde, p anisidine, and di(3 pentyl)phosphite in the presence of newly developed chiral phosphoric acid It. The corresponding p branched a amino phosphonates were obtained in high diastereo and enantioselectivities, especially for the aldehydes bearing a secondary alkyl group at the a position. 

Considering that the a-proton-exchange of racemic azlactones occurred rapidly in the presence of a tertiary amine base. Song and coworkers demonstrated enan-tioselective synthesis of a-deuterated a-amino acids via dynamic kinetic resolution (DKR) of azlactones with EtOD using cinchona-derived dimeric squaramide catalyst 33 (Scheme 10.34) [112]. The authors noted that by increasing the amount of EtOD, the level of deuterium incorporation increased, whereas the enantioselectivity decreased. By using 50 equivalents of EtOD, the products were obtained with... 

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