An improved chiroporphyrin shift reagent for the enantiomeric assay of amino acid derivatives by 1H NMR spectroscopy: evaluation of iodorhodium(III) tetramethylchiroporphyrin

2002 ◽  
Vol 06 (06) ◽  
pp. 396-402 ◽  
Author(s):  
Magalie Claeys-Bruno ◽  
Jacques Pécaut ◽  
Michel Bardet ◽  
Jean-Claude Marchon
Keyword(s):  
Amino Acid ◽  
Nmr Spectroscopy ◽  
Kinetic Resolution ◽  
Dimethyl Ester ◽  
Spectroscopic Studies ◽  
Shift Reagent ◽  
Strong Impact ◽  
H Nmr ◽  
Derivatizing Agent ◽  
Amino Acid Mixtures

1 H NMR spectroscopic studies of amino ester complexation indicate that iodorhodium(III) tetramethylchiroporphyrin RhI(TMCP) has a single axial site available for the coordination of amine groups, and that it retains its iodo ligand trans to the coordinated amine. This conclusion is confirmed by the X-ray structure of the 1:1 adduct of n-propylamine with RhI(TMCP). This stoichiometry of amine binding makes RhI(TMCP) a superior chiral derivatizing agent relative to CoCl ( TMCP ), which gives 1:2 adducts. It may have a strong impact in the utilization of RhI(TMCP) for the enantiomeric assay of amino acid mixtures by 1 H NMR spectroscopy. Axial exchange of the (R)- and (S)-enantiomers of aspartic acid dimethyl ester on RhI(TMCP) is moderately slow, and equilibrium is reached in a few minutes without kinetic resolution.

scholarly journals The Bull–James assembly as a chiral auxiliary and shift reagent in kinetic resolution of alkyne amines by the CuAAC reaction

2016 ◽  
Vol 14 (46) ◽  
pp. 10778-10782 ◽  
Author(s):  
William D. G. Brittain ◽  
Brette M. Chapin ◽  
Wenlei Zhai ◽  
Vincent M. Lynch ◽  
Benjamin R. Buckley ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Boronic Acid ◽  
Kinetic Resolution ◽  
Enantiomeric Excess ◽  
Shift Reagent ◽  
Chiral Auxiliary ◽  
H Nmr ◽  
Chiral Shift Reagent ◽  
Cuaac Reaction

The Bull–James boronic acid assembly is used simultaneously as a chiral auxiliary for kinetic resolution and as a chiral shift reagent for in situ enantiomeric excess (ee) determination by 1H NMR spectroscopy.

Chemical Shift Nonequivalence of Enantiomers of Amino Acid Derivatives in 1H NMR and 19F NMR Spectroscopy Induced by L-Chirasil- Val.

1992 ◽  
Vol 47 (7) ◽  
pp. 1034-1036 ◽  
Author(s):  
Bernhard Koppenhoefer ◽  
Michael Hummel
Keyword(s):  
Amino Acid ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Methyl Esters ◽  
Enantiomeric Purity ◽  
Peak Splitting ◽  
H Nmr ◽  
Acid Methyl ◽  
Amino Acid Methyl Esters

Enantiomers of N-trifluoroacetyl-amino acid methyl esters in CC14 solution, after addition of the chiral polysiloxane (L)-Chirasil-Val, display a chemical shift nonequivalence ΔΔδ in both 1H NMR and 19F NMR spectroscopy. The effects found for the leucine and valine derivatives can be correlated with the thermodynamic parameters of interaction in the undiluted system, as determined by gas chromatography. In CDC13 solution, no peak splitting was observed. The method is potentially useful for the determination of the enantiomeric purity of substrates of low volatility.

scholarly journals Chiral mono- and dicarbamates derived from ethyl (S)-lactate: convenient chiral solvating agents for the direct and efficient enantiodiscrimination of amino acid derivatives by 1H NMR spectroscopy

RSC Advances ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 4869-4875 ◽  
Author(s):  
Federica Balzano ◽  
Gloria Uccello-Barretta
Keyword(s):  
Amino Acid ◽  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Amino Acid Derivatives ◽  
H Nmr

New lactate-based CSAs for 1H NMR enantiodifferentiation of amino acid derivatives.

Nucleoside analogs involving modifications in the carbohydrate ring: nuclear magnetic resonance spectroscopic studies

1985 ◽  
Vol 63 (8) ◽  
pp. 2162-2168 ◽  
Author(s):  
Walter A. Szarek ◽  
B. Mario Pinto ◽  
Masaharu Iwakawa
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Nucleoside Analogs ◽  
Spectroscopic Properties ◽  
Spectroscopic Studies ◽  
Nucleoside Analog ◽  
H Nmr ◽  
Acyclic Nucleoside ◽  
C Nmr

The concomitant use of 1H nmr and 13C nmr spectroscopy as a probe of structure, stereochemistry, and conformation of several nucleoside analogs derived from 1-oxa-4-thiacyclohexane is described. The 1H nmr spectroscopic properties of an acyclic nucleoside analog derived from uridine are also described.

Zirconocene-mediated selective synthesis of 1,4-bis(alkynyl)benzenes

2020 ◽  
Vol 44 (9-10) ◽  
pp. 571-575
Author(s):  
Bo Zhang ◽  
Hongmei Qu ◽  
Zhongxuan Li ◽  
Yuanyuan Zhai ◽  
Xiaolu Zhou ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dimethyl Ester ◽  
Acid Ethyl Ester ◽  
Coupling Reactions ◽  
Benzene Derivatives ◽  
Phenylene Ethynylene ◽  
H Nmr ◽  
Vis Spectroscopy ◽  
High Yields ◽  
C Nmr

A series of novel 1,4-bis(alkynyl)benzene derivatives were synthesized from trimethylsilyl-substituted alkynes by the mediation of zirconocene with excellent regioselectivity in high yields. The 3,6-bis(trimethylsilyl)-4,5-dialkylphthalic acid dimethyl esters were prepared by cycloaddition of 2,5-bis(trimethylsilyl)zirconacyclopentadienes to dimethyl acetylenedicarboxylate. After iodination with iodine monochloride, 3,6-diiodo-4,5-dialkylphthalic acid dimethyl esters reacted with terminal alkynes to prepare the corresponding 1,4-bis(alkynyl)benzene derivatives by Sonogashira coupling reactions. After removal of trimethylsilyl, 4,5-dibutyl-3,6-bis(ethynyl)phthalic acid dimethyl ester (compound 3) reacted with 4-iodobenzoic acid ethyl ester and 2-iodothiophene, respectively, to obtain the corresponding products 4a and 4c. Compound 3 can be extended to higher oligomers, which reacted with 1-bromo-4-iodobenzene and phenylacetylene in a stepwise manner under Sonogashira conditions to give the phenylene-ethynylene oligomer 5 in an isolated yield of 85%. The structures of the products were confirmed by 1H NMR spectroscopy, 13C NMR spectroscopy, and MS. The optical properties of the 1,4-bis(alkynyl)benzene derivatives were studied by UV-Vis spectroscopy and fluorescence spectra. The results indicated that some can be developed into potential photovoltaic materials.

13C NMR spectroscopy of amino acid mixtures

1982 ◽  
Vol 16 (1) ◽  
pp. 71-74
Author(s):  
S. V. Tarabakin ◽  
V. P. Panov ◽  
I. G. Sarkisova ◽  
E. V. Bykova
Keyword(s):  
Amino Acid ◽  
Nmr Spectroscopy ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Amino Acid Mixtures

13C NMR spectroscopy of amino acid mixtures. II. Amino acid composition of preparations based on liver hydrolyzates

1981 ◽  
Vol 15 (3) ◽  
pp. 218-221
Author(s):  
S. V. Tarabakin ◽  
V. P. Panov ◽  
V. I. Dubrovin ◽  
I. G. Sarkisova ◽  
E. V. Bykova
Keyword(s):  
Amino Acid ◽  
Nmr Spectroscopy ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Amino Acid Mixtures

1H and 13C NMR Spectroscopic Studies of the Complexation of Phenylenedioxydiacetamides with Calcium and Potassium Cations in Solution

1984 ◽  
Vol 39 (10) ◽  
pp. 1375-1379 ◽  
Author(s):  
Whei Oh Lin ◽  
Maria C. B. V. de Souza ◽  
Helmut G. Alt
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Methylene Chloride ◽  
Spectroscopic Studies ◽  
Acetonitrile Solution ◽  
Chelating Ligands ◽  
1H And 13C Nmr ◽  
Coordination Modes ◽  
H Nmr ◽  
C Nmr

Phenylenedioxydiacetamides are examples of noncyclic ionophors that are able to form 2:1 complexes with the cations Ca2+ and K+ in acetone, methylene chloride or acetonitrile solution. The chelation abilities and coordination modes of 12 derivatives were investigated systematically by IR, 1H NMR and 13C NMR spectroscopy. The results indicate that only the 1,2-phenylenedioxydiacetam ides function as ligands; while the 1,3-derivatives do not coordinate. The ionophors 1-8 act as tetradentate chelating ligands with all four oxygen atoms involved in bonding to the cation. Irrespective of its charge, each cation is coordinated by two ionophors.

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