30358-55-5Relevant academic research and scientific papers
Synthesis of dipeptides containing α-substituted amino acids; their use as chiral ligands in Lewis-acid-catalyzed reactions
Kaptein, Bernard,Monaco, Vania,Broxterman, Quirinus B.,Schoemaker, Hans E.,Kamphuis, Johan
, p. 231 - 238 (1995)
L-α-Methylphenylalanine, obtained by enzymatic resolution of the corresponding racemic amide with amidase from Ochrobactrum anthropi NCIMB 40321, was used in the synthesis of dipeptides containing α-substituted amino acids.The 2-hydroxynaphthalene-1-carboxaldehyde Schiff bases of the dipeptides (1 and 2) were tested as Ti(IV) and Al(III) complexes in asymmetric Lewis-acid-catalyzed reactions.Only the Al(III) complex of 2 showed moderate enantioselectivity in the cyanation reaction of benzaldehyde with TMS-CN.
Selector screening for enantioseparation of DL-α-methyl phenylglycine amide by liquid-liquid extraction
Schuur, Boelo,Blahu?iak, Marek,Vitasari, Caecilia R.,Grambli?ka, Michal,De Haan, André B.,Visser, Ton J.
, p. 123 - 130 (2015/03/04)
Enantioseparation through liquid extraction technology is an emerging field, e.g., enantioseparations of amino acids (and derivatives thereof), amino alcohols, amines, and carboxylic acids have been reported. Often, when a new selector is developed, the versatility of substrate scope is investigated. From an industrial point of view, the problem is typically approached the other way around, and for a target racemate, a selector needs to be found in order to accomplish the desired enantioseparation. This study presents such a screening approach for the separation of the enantiomers of DL-α-methyl phenylglycine amide (DL-α-MPGA), a model amide racemate with high industrial relevance. Chiral selectors that were reported for other classes of racemates were investigated, i.e., several macrocyclic selectors and Pd-BINAP complexes. It appeared very challenging to obtain both high extraction yields and good enantioselectivity for most selectors, but Pd-BINAP-based selectors performed well, with enantioselectivities up to 7.4 with an extraction yield of the desired enantiomer of 95.8%. These high enantioselectivities were obtained using dichloromethane as solvent. Using less volatile chlorobenzene or 1-chloropentane, reasonable selectivities of up to 1.7 were measured, making these the best alternative solvents for dichloromethane.
Synthesis of optically active α-methylamino acids and amides through biocatalytic kinetic resolution of amides
Wang, Mei-Xiang,Liu, Jun,Wang, De-Xian,Zheng, Qi-Yu
, p. 2409 - 2416 (2007/10/03)
Catalyzed by Rhodococcus sp. AJ270, a nitrile hydratase and amidase containing microbial whole-cell catalyst, under very mild conditions, a number of racemic α-methylamino amides were resolved into the corresponding optically active (S)-(+)-α-methylamino acids and (R)-(-)-α- methylamino amides. The steric requirement of the amidase against α-amino phenylacetamides bearing methyl group(s) at α-amino nitrogen and/or α-carbon was also studied. Coupled with the chemical hydrolysis of amide, the biotransformation process provided a direct synthesis of α-methylamino acids in both enantiomeric forms from readily available racemic amides.
