7352-06-9Relevant articles and documents
Intermolecular Amine Transfer to Enantioenriched trans-3Phenylglycidates by an α/β-Aminomutase to Access Both anti-Phenylserine Isomers
Shee, Prakash K.,Yan, Honggao,Walker, Kevin D.
, p. 15071 - 15082 (2020/12/21)
β-Hydroxy-α-amino acids are noncanonical amino acids with two stereocenters and with useful applications in the pharmaceutical and agrochemical sectors. Here, a 5-methylidene-3,5-dihydro-4H-imidazol-4-one-dependent aminomutase from Taxus canadensis (TcPAM) was repurposed to transfer the amino group irreversibly from (2S)-styryl-α-alanine to exogenously supplied trans-3-phenylglycidate enantiomers, producing anti-phenylserines stereoselectively. TcPAM catalysis inverted the intrinsic regioselective chemistry from amination at Cβ to Cα of enantioenriched trans-3-phenylglycidates to make phenylserine predominantly (97%)phenylisoserine (～3% relative abundance). Gas chromatography?mass spectrometry analysis of the chiral auxiliary derivatives of the biocatalyzed products confirmed that the amine transfer was stereoselective for each glycidate enantiomer. TcPAM converted (2S,3R)-3-phenylglycidate to (2S)-anti-phenylserine predominantly (89%) and (2R,3S)-3-phenylglycidate to (2R)-anti-phenylserine (88%)their antipodes, with inversion of the configuration at Cα in each case. Both glycidate enantiomers formed a small amount (～10%) of syn-phenylserine by retaining the configuration at Cα. The minor syn-isomer likely came from a β-hydroxy oxiranone intermediate formed by intramolecular ring opening of the oxirane ring by the carboxylate before amine transfer. TcPAM had a slight preference toward (2S,3R)-3-phenylglycidate, which was turned(kcat = 0.3 min?1) 1.5 times faster than the (2R,3S)-glycidate (kcat = 0.2 min?1). The catalytic efficiencies (kcatapp/KMapp ≈ 20 M?1s?1) of TcPAM for the antipodes were similar. The kinetic data supported a two-substrate ping-pong mechanism for the amination of the phenylglycidates, with competitive inhibition at higher glycidate substrate concentrations.
Application of Threonine Aldolases for the Asymmetric Synthesis of α-Quaternary α-Amino Acids
Blesl, Julia,Trobe, Melanie,Anderl, Felix,Breinbauer, Rolf,Strohmeier, Gernot A.,Fesko, Kateryna
, p. 3453 - 3458 (2018/07/30)
We report the synthesis of diverse β-hydroxy-α,α-dialkyl-α-amino acids with perfect stereoselectivity for the α-quaternary center through the action of l- and d-specific threonine aldolases. A wide variety of aliphatic and aromatic aldehydes were accepted by the enzymes and conversions up to >80 % were obtained. In the case of d-selective threonine aldolase from Pseudomonas sp., generally higher diastereoselectivities were observed. The applicability of the protocol was demonstrated by performing enzymatic reactions on preparative scale. Using the d-threonine aldolase from Pseudomonas sp., (2R,3S)-2-amino-3-(2-fluorophenyl)-3-hydroxy-2-methylpropanoic acid was generated in preparative amounts in one step with a diastereomeric ratio >100 favoring the syn-product. A Birch-type reduction enabled the reductive removal of the β-hydroxy group from (2S)-2-amino-3-hydroxy-2-methyl-3-phenylpropanoic acid to generate enantiopure l-α-methyl-phenylalanine via a two-step chemo-enzymatic transformation.
Biocatalytic Synthesis of Enantiopure β-Methoxy-β-arylalanine Derivatives
Fan, Shiming,Liu, Shouxin,Zhang, Hubo,Liu, Ying,Yang, Yihuang,Jin, Longyi
, p. 5591 - 5597 (2014/10/15)
Chiral β-hydroxy-β-arylalanine and β-methoxy-β-arylalanine derivatives, which occur widely in marine nature products, were stereoselectively synthesized with 99 % ee values. The two erythro isomers were prepared by L- or D-aminoacylase-catalyzed resolution of the corresponding N-acetyl derivatives, whereas the two threo isomers were obtained only by D-aminoacylase-catalyzed resolution of the derivatives. erythro-β-Hydroxy-β-arylalanine derivatives were prepared by diastereoselective hydrogenation of ethyl 2-(hydroxyimino)-3-oxo-3-arylpropanoates, which were in turn acquired by the oximation of ethyl 3-oxo-3-arylpropanoates with ethyl nitrite in the presence of nano-K2CO3 with yields of 72 % to 80 %. β-Methoxy-β-arylalanine derivatives were synthesized through Williamson reactions between the corresponding β-hydroxy-β-arylalanines and iodomethane with silver oxide as base.
