7352-07-0Relevant articles and documents
Direct asymmetric reductive amination of α-keto acetals: A platform for synthesizing diverse α-functionalized amines
Chiu, Pauline,Shi, Yongjie,Wang, Chenhan,Wang, Jingxin,Yang, Feifan,Yin, Qin,Zhang, Xumu
supporting information, p. 513 - 516 (2022/01/22)
We report an efficient and straightforward method to synthesize enantio-enriched N-unprotected α-amino acetals via ruthenium-catalyzed direct asymmetric reductive amination. The α-amino acetal products are versatile and valuable platform molecules that can be converted to the corresponding α-amino acids, amino alcohols, and other derivatives by convenient transformations.
Palladium-catalyzed asymmetric decarboxylative allylation of azlactone enol carbonates: Fast access to enantioenriched α-allyl quaternary amino acids
Serra, Massimo,Bernardi, Eric,Marrubini, Giorgio,De Lorenzi, Ersilia,Colombo, Lino
, p. 732 - 741 (2019/01/09)
We report a fast protocol for the synthesis of enantioenriched quaternary 4-allyl oxazol-5-ones. The key step is a Pd-catalyzed enantioselective Tsuji allylation of azlactone allyl enol carbonates, which can be easily prepared starting from racemic α-amino acids. The use of (R,R)-DACH-phenyl Trost chiral ligand allowed the attainment of the allylated derivatives in very good yields (83–98 %) and with ee up to 85 %. Scaling up the allylation protocol to gram quantities did not affect the yields end ee values. The produced 4-allyl azlactones can be converted into the corresponding quaternary amino acids or submitted to further synthetic elaborations exploiting the allyl moiety as a handle for the attachment of alkyl and aryl groups. After hydrolysis of the azlactone ring, the zwitterionic amino acids can be attained in enantiopure or nearly optically pure form through only one recrystallization step.
Dynamic Kinetic Resolution of N-Protected Amino Acid Esters via Phase-Transfer Catalytic Base Hydrolysis
Yamamoto, Eiji,Wakafuji, Kodai,Furutachi, Yuho,Kobayashi, Kaoru,Kamachi, Takashi,Tokunaga, Makoto
, p. 5708 - 5713 (2018/05/30)
Asymmetric base hydrolysis of α-chiral esters with synthetic small-molecule catalysts is described. Quaternary ammonium salts derived from quinine were used as chiral phase-transfer catalysts to promote the base hydrolysis of N-protected amino acid hexafluoroisopropyl esters in a CHCl3/NaOH (aq) via dynamic kinetic resolution, providing the corresponding products in moderate to good yields (up to 99%) with up to 96:4 er. Experimental and computational mechanistic studies using DFT calculation and pseudotransition state (pseudo-TS) conformational search afforded a TS model accounting for the origin of the stereoselectivity. The model suggested π-stacking and H-bonding interactions play essential roles in stabilizing the TS structures.
Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid
Yamada, Kohei,Kamimura, Naoto,Kunishima, Munetaka
supporting information, p. 1478 - 1485 (2017/08/02)
A novel method for the synthesis of trisubstituted oxazoles via a one-pot oxazole synthesis/Suzuki–Miyaura coupling sequence has been developed. One-pot formation of 5-(triazinyloxy)oxazoles using carboxylic acids, amino acids and a dehydrative condensing reagent, DMT-MM, followed by Ni-catalyzed Suzuki–Miyaura coupling with boronic acids provided the corresponding 2,4,5-trisubstituted oxazoles in good yields.
Asymmetric synthesis of α- And β-amino acids by diastereoselective addition of triorganozincates to N-(tert-butanesulfinyl) imines
Almansa, Raquel,Collados, Juan F.,Guijarro, David,Yus, Miguel
experimental part, p. 1421 - 1431 (2010/11/02)
The diastereoselective addition of triorganozincates to (R)-N-(tert-butanesulfinyl)imines has been used as a key step to achieve the synthesis of highly enantiomerically enriched N-protected α- and β-amino acids. Desulfinylation of the addition products followed by benzoylation of the nitrogen atom of the obtained primary amines and oxidation of one of the substituents on the carbon atom connected to the nitrogen complete the sequence. Using the same configuration in the sulfinyl chiral auxiliary, α-amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. α,α- Disubstituted α-amino esters with high enantiomeric purity can also be prepared when α-imino esters are the starting substrates.
Application of the addition of triorganozincates to N-(tert-butanesulfinyl)imines to the enantioselective synthesis of α-amino acids
Almansa, Raquel,Guijarro, David,Yus, Miguel
scheme or table, p. 4188 - 4190 (2009/12/01)
Highly enantiomerically enriched N-protected α-amino acids can be easily prepared from optically pure N-(tert-butanesulfinyl)imines by a four-step sequence involving: diastereoselective addition of a triorganozincate to the imine, removal of the sulfinyl group, benzoylation of the nitrogen atom of the obtained primary amine and oxidation of one of the substituents on the carbon atom α to the nitrogen. Using the same configuration in the sulfinyl chiral auxiliary, amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. α,α-Disubstituted α-amino esters with high optical purity can also be prepared by the diastereoselective addition of trialkylzincates to α-imino esters.
Combining Magnetic Resonance Spectroscopies, Mass Spectrometry, and Molecular Dynamics: Investigation of Chiral Recognition by 2,6-di-O-Methyl-β-cyclodextrin
Franchi, Paola,Lucarini, Marco,Mezzina, Elisabetta,Pedulli, Gian Franco
, p. 4343 - 4354 (2007/10/03)
EPR spectroscopy has been employed to investigate the formation of complexes between heptakis-(2,6-O-dimethyl)-β-cyclodextrin (DM-β-CD) and different enantiomeric pairs of chiral nitroxides of general structure PhCH2N(O·)CH(R)R′. Accurate equilibrium measurements of the concentrations of free and included radicals afforded the binding constant values for these nitroxides. The relationship between the stereochemistry of the DM-β-CD complexes and the thermodynamics of complexation was elucidated by correlating EPR data with 1H-1H NOE measurements carried out on the complexes between DM-β-CD and the structurally related amine precursors of nitroxides. NOE data suggested that inclusion of the stereogenic center in the DM-β-CD cavity occurs only when the R substituent linked to the chiral carbon contains an aromatic ring. For these types of complexes, molecular dynamics simulation indicated that the depth of penetration of the stereogenic center into the cyclodextrin cavity is determined by the nature of the second substituent (R′) at the asymmetric carbon and is responsible for the observed chiral selectivity. Analysis of mass spectra showed that, for the presently investigated amines, electrostatic external adducts of CDs with protonated amines are detected by ESI-MS.
Beauveria bassiana ATCC 7159 contains an L-specific α-amino acid benzamidase
Holland, Herbert L.,Andreana, Peter R.,Salehzadeh-Asl, Reza,Van Vliet, Aaron,Ihasz, Nancy J.,Brown, Frances M.
, p. 667 - 672 (2007/10/03)
Biotransformation of a series of racemic N-benzoyl α-amino acids by the fungus Beauveria bassiana ATCC 7159 results in isolation of the corresponding D-amino acid benzamides in high enantiomeric purity and yield.
Synthesis of (S)- and (R)-1-(2-furyl)alkylamines and (S)- and (R)-α- amino acids through the addition of organometallic reagents to imines derived from (S)-Valinol
Alvaro, Giuseppe,Martelli, Gianluca,Savoia, Diego,Zoffoli, Andrea
, p. 1773 - 1777 (2007/10/03)
(S)-1-(2-Furyl)alkylamines were prepared through the addition of organometallic reagents to the imine derived from 2-furaldehyde and (S)- valinol, previous protection of the auxiliary hydroxy group as trimethylsilyl ether, followed by removal of the auxiliary. Then, protection of the primary amine as tosylamide or benzamide and oxidation of the furan ring gave the N- derivatives of (S)-α-amino acids. (R)-N-Benzoylphenylglycine was prepared from the benzaldimine, where the hydroxy group was protected as the tert- butyldimethylsilyl ether, through addition of 2-furyllithium.
N-Acylated α-Amino Acids as Novel Oral Delivery Agents for Proteins
Leone-Bay, Andrea,Santiago, Noemi,Achan, Douglas,Chaudhary, Kiran,DeMorin, Frenel,et al.
, p. 4263 - 4269 (2007/10/03)
A series of N-acylated α-amino acids were synthesized and shown to improve the oral delivery of two protein drugs, salmon calcitonin (sCT) and interferon-α.Forty-five compounds in this series were tested in vivo in rats and primates.A significant positive
