- Reductive Alkylation of Amines with Carboxylic Ortho Esters
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We have demonstrated for the first time that carboxylic ortho esters could be used as an alkylating agent in the reductive alkylation of amines. A variety of amines, including amino acid esters, were alkylated affording mono-alkylated products with high selectivity in practical to high yields using standard heterogeneous catalysts. By applying acyclic ortho esters alkylation was completed at room temperature. (Figure presented.).
- Kadyrov, Renat,Moebus, Konrad
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supporting information
p. 3352 - 3357
(2020/07/04)
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- Ketoprofen-based ionic liquids: Synthesis and interactions with bovine serum albumin
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The development of ionic liquids based on active pharmaceutical ingredients (API-ILs) is a possible solution to some of the problems of solid and/or hydrophobic drugs such as low solubility and bioavailability, polymorphism and an alternative route of administration could be suggested as compared to the classical drug. Here, we report for the first time the synthesis and detailed characterization of a series of ILs containing a cation amino acid esters and anion ketoprofen (KETO-ILs). The affinity and the binding mode of the KETO-ILs to bovine serum albumin (BSA) were assessed using fluorescence spectroscopy. All compounds bind in a distance not longer than 6.14 nm to the BSA fluorophores. The estimated binding constants (KA) are in order of 105 L mol-1, which is indicative of strong drug or IL-BSA interactions. With respect to the ketoprofen-BSA system, a stronger affinity of the ILs containing l-LeuOEt, l-ValOBu, and l-ValOEt cation towards BSA is clearly seen. Fourier transformed infrared spectroscopy experiments have shown that all studied compounds induced a rearrangement of the protein molecule upon binding, which is consistent with the suggested static mechanism of BSA fluorescence quenching and formation of complexes between BSA and the drugs. All tested compounds were safe for macrophages.
- ?wi?tek, Ewelina,Angelov, Ivan,Guncheva, Maya,Janus, Ewa,Kardaleva, Proletina,Klebeko, Joanna,Ossowicz, Paula,Yancheva, Denitsa
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- Stereospecific Synthesis of 3,4-Dihydro-2 H-naphtho-1,4-oxazin-2-ones by Unification of Benzoxepine-4-carboxylates with Chiral Amino Acid Ethyl Esters
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A novel and efficient stereocontrolled method has been developed for the preparation of chiral 3,4-dihydro-2H-naphtho[1,2-b][1,4]oxazin-2-ones by the reaction of benzoxepine-4-carboxylates with chiral amino acid ethyl esters for the first time. The chiral 3,4-dihydro-2H-naphtho-1,4-oxazinones have been achieved in one step by the formation of C-N, C-C, and C-O bonds.
- Bhimapaka, China Raju,Kasagani, Veera Prasad,Kurma, Siva Hariprasad
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supporting information
p. 2976 - 2983
(2020/03/23)
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- Design and synthesis of a s-triazene based asymmetric organocatalyst and its application in enantioselective alkylation
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A very efficient chiral organocatalyst was prepared from the readily available cyanuric chloride. The asymmetric catalyst exhibited a highly enantioselective catalytic performance for the alkylation of a glycinate Schiff base, which provides a useful procedure for the enantioselective synthesis of structurally diverse natural and unnatural α-alkyl-α-amino acids.
- Mangawa, Shrawan K.,Singh, Ashawani K.,Awasthi, Satish K.
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p. 61144 - 61147
(2015/08/03)
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- Stereochemistry and conformation of skyllamycin, a non-ribosomally synthesized peptide from streptomyces sp. Acta 2897
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Skyllamycin is a non-ribosomally synthesized cyclic depsipeptide from Streptomyces sp. Acta 2897 that inhibits PDGF-signaling. The peptide scaffold contains an N-terminal cinnamoyl moiety, a β-methylation of aspartic acid, three β-hydroxylated amino acids and one rarely occurring α-hydroxy glycine. With the exception of α-hydroxy glycine, the stereochemistry of the amino acids was assigned by comparison to synthetic reference amino acids applying chiral GC-MS and Marfey-HPLC analysis. The stereochemistry of α-hydroxy glycine, which is unstable under basic and acidic conditions, was determined by conformational analysis, employing a combination of data from NOESY-NMR spectroscopy, simulated annealing and free MD simulations. The simulation procedures were applied for both R- and S-configured α-hydroxy glycine of the skyllamycin structure and compared to the NOESY data. Both methods, simulated annealing and free MD simulations independently support S-configured α-hydroxy glycine thus enabling the assignment of all stereocenters in the structure of skyllamycin and devising the role of two-component flavin dependent monooxygenase (Sky39) as S-selective.
- Schubert, Vivien,Di Meo, Florent,Saaidi, Pierre-Loic,Bartoschek, Stefan,Fiedler, Hans-Peter,Trouillas, Patrick,Suessmuth, Roderich D.
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p. 4948 - 4955
(2014/05/06)
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- A New Chiral Glycine Synthon. Synthesis, X-Ray Structure of (-)-(2S,4R)-2-Ethoxycarbonyl-4-phenyl-1,3-oxazolidine and Diastereoselective Nucleophilic Ring Opening to (R)-Ethyl α-Amino Carboxylates.
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Condensation of (R)-N-benzyl-2-phenylglycinol 1 with the methyl hemiacetal of ethyl glyoxylate leads to (2S,4R)-2-ethoxycarbonyl-4-phenyl-1,3-oxazolidine 2 as the major product, obtained as a pure enantiomer after column chromatography.Compound 2 is stereoselectively cleaved by dialkylzinc reagents, prepared from alkylmagnesium iodides and ZnCl2, with moderate to good d.e. (72-94 percent).These compounds, after separation by column chromatography and debenzylation by hydrogenolysis in the presence of 10percent Pd on carbon, lead to enantiomerically pure ethyl α-amino carboxylates with good chemical yields. Key words: Chiral Oxazolidines, alpha-amino Esters, Chiral Glycine Synthon, Ring Opening, Asymmetric Synthesis
- Andres, Celia,Gonzalez, Alfonso,Pedrosa, Rafael,Perez-Encabo,Garcia-Granda, Santiago,et al.
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p. 4743 - 4746
(2007/10/02)
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