22435-99-0Relevant academic research and scientific papers
Diastereoselective Synthesis of Unnatural Amino Acids by Alkylation of α- Tert-Butanesulfinamide Auxiliary-Bound Enolates
Dwulet, Natalie C.,Zolfaghari, Tina A.,Brown, Molly L.,Cannon, Jeffrey S.
, p. 11510 - 11518 (2018/09/27)
A new chiral auxiliary for the diastereoselective alkylation of amino ester enolates that takes advantage of chiral information stored on the enolate side of the amino ester substrate has been developed. Chiral α-sulfinamido esters were alkylated under basic conditions in good yields (up to 90%) and good to high diastereoselectivities (generally >6:1) to provide unnatural mono- and α,α-disubstituted amino acid derivatives. This auxiliary allowed for the ready conversion of ester functionality without the need for esoteric reagents. Furthermore, the auxiliary is easily removed to provide enantiopure amino acids. Computational studies revealed that a chelated transition state governs electrophile addition from the convex face of a transient bicyclic intermediate. This method allows ready access to enantioenriched natural and unnatural amino acids.
Mitsunobu approach to the synthesis of optically active α,α-disubstituted amino acids
Green, Jonathan E.,Bender, David M.,Jackson, Stona,O'donnell, Martin J.,Mccarthy, James R.
supporting information; experimental part, p. 807 - 810 (2009/08/08)
Chiral tertiary α-hydroxy esters of known stereochemical configuration were transformed to α-azido esters by Mitsunobu reaction with HN3. Optimization of this reaction was shown to proceed at room temperature with high chemical yield using 1,1-(azodicarbonyl)dipiperidine (ADDP) and trimethylphosphine (PMe3). Complete inversion of configuration was observed at the α-carbon. Several α,α- disubstituted amino acids were synthesized in high overall chemical yield and optical purity.
Highly enantioselective alkylation of glycine methyl and ethyl ester derivatives under phase-transfer conditions: Its synthetic advantage
Ooi, Takashi,Uematsu, Yukitaka,Maruoka, Keiji
, p. 1675 - 1678 (2007/10/03)
Phase-transfer alkylation of the benzophenone Schiff base of glycine methyl or ethyl ester (2) was found to be catalyzed by 3,4,5-F 3-C6H2-NAS-Br [(S,S)-1] with high efficiency and excellent enantioselectivity. This procedure allows facile derivatization of the resulting alkylation products to other synthetically useful chiral building blocks.
Enantioselective biotransformation of α,α-disubstituted dinitriles to the corresponding 2-cyanoacetamides using Rhodococcus sp. CGMCC 0497
Wu, Zhong-Liu,Li, Zu-Yi
, p. 2133 - 2142 (2007/10/03)
A new application of nitrile-converting enzymes in the synthesis of optically active α,α-disubstituted-α-cyanoacetamides from α,α-disubstituted-malononitriles with whole cells of Rhodococcus sp. CGMCC 0497 is described. The products were obtained with enantiomeric excesses of up to >99%, and yields of up to 53%. They are very useful chiral intermediates especially for the synthesis of chiral α,α-disubstituted amino acids but have never been synthesized directly by chemical or enzymatic methods.
Synthesis, resolution and absolute configuration determination of (S)- and (R)-4-formyl-5-hydroxyparacyclophane and its application in the asymmetric synthesis of α-amino acids
Antonov, Dmitri Yu.,Belokon, Yuri N.,Ikonnikov, Nikolai S.,Orlova, Svetlana A.,Pisarevsky, Aleksander P.,et al.
, p. 1873 - 1880 (2007/10/02)
Racemic (R,S)-4-formyl-5-hydroxyparacyclophane (FHPC) was resolved into enantiomers via its Schiff's base with (S)- and (R)-α-phenylethylamine (α-PEAM) and its absolute configuration was determined by an X-ray diffraction structural study.Scalemic FHPC or its derivatives can be used as chiral auxiliaries for the asymmetric synthesis of β-hydroxy-α-amino acids and α-methylphenylalanine with ees ranging mostly from 45 to 98percent.
Chemo-Enzymic Synthesis of Optically Active α,α-Disubstituted α-Amino Acids
Liu, Weiguo,Ray, Paul,Benezra, Steven A.
, p. 553 - 560 (2007/10/02)
A series of α,α-disubstituted α-amino esters was chemically synthesized and then resolved through enantioselective hydrolysis catalysed by a new enzyme isolated from crude Humicola langinosa lipase.This enzyme only accepts free amino esters as substrates with neither lipase activity toward olive oil nor esterase activity toward o-nitrophenyl butyrate.It is unique in that it successfully catalyses the resolution of amino esters with two large α-alkyl groups including aliphatic, aromatic and cyclic amino esters.Examples of resolutions where the alkyl groups differ in size by as little as a single carbon atom have been demonstrated.For determination of absolute configuration, some of the optically active α,α-disubstituted amino acids were also prepared through Schoellkopf's asymmetric synthesis and the structures were verified by X-ray crystallography.A model depicting the substrate binding site of the enzyme is proposed.
Biocatalytic Resolution of Tertiary α-Substituted Carboxylic Acid Esters: Efficient Preparation of a Quaternary Asymmetric Carbon Center
Yee, Christopher,Blythe, Todd A.,McNabb, Thomas J.,Walts, Alan E.
, p. 3525 - 3527 (2007/10/02)
A method for resolving a variety of tertiary α-substituted carboxylic acid esters employing a previously undescribed enzyme is reported.
