A concise approach for determining the relative configuration of H-7 and H-8 in 8,4′-oxyneolignans by 1H NMR spectroscopy

2019 ◽  
Vol 6 (7) ◽  
pp. 886-891 ◽  
Author(s):  
Ya-Nan Yang ◽  
Bing Han ◽  
Peng-Fei Yang ◽  
Zi-Ming Feng ◽  
Jian-Shuang Jiang ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Relative Configuration ◽  
Chemical Shift Difference

The chemical shift difference between H-9a and H-9b can be used to accurately and rapidly determine the relative configuration of H-7 and H-8 in three types of 8,4′-oxyneolignan glucosides.

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

1H NMR spectroscopy of titania. Chemical shift assignments for hydroxy groups in crystalline and amorphous forms of TiO2

1996 ◽  
Vol 92 (15) ◽  
pp. 2791 ◽  
Author(s):  
Mark Crocker ◽  
Ruud H. M. Herold ◽  
Antonio E. Wilson ◽  
Munro Mackay ◽  
Cees A. Emeis ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Chemical Shift Assignments ◽  
Amorphous Forms ◽  
Hydroxy Groups

Rapid Approaches for Assignment of the Relative Configuration in 1-Oxygenated 1,2-Diarylpropan-3-ols by 1H NMR Spectroscopy

2021 ◽  
Vol 84 (1) ◽  
pp. 20-25
Author(s):  
Le Zhou ◽  
Rui Guo ◽  
Han Zhang ◽  
Li-Wei Lu ◽  
Ye-Qing Du ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Relative Configuration

An Efficient Method for Determining the Relative Configuration of Furofuran Lignans by 1H NMR Spectroscopy

2018 ◽  
Vol 81 (4) ◽  
pp. 1023-1028 ◽  
Author(s):  
Si-Yuan Shao ◽  
Ya-Nan Yang ◽  
Zi-Ming Feng ◽  
Jian-Shuang Jiang ◽  
Pei-Cheng Zhang
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Efficient Method ◽  
1H Nmr Spectroscopy ◽  
Relative Configuration

Introducing a novel procedure for peak alignment in one-dimensional 1H-NMR spectroscopy: a prerequisite for chemometric analyses of wine samples

2020 ◽  
Vol 12 (28) ◽  
pp. 3626-3636
Author(s):  
Keshav Kumar ◽  
Ralf Schweiggert ◽  
Claus-Dieter Patz
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Current Work ◽  
Peak Alignment ◽  
One Dimensional ◽  
H Nmr

In the current work, a novel procedure for correcting the peak drifts of 1H-NMR was introduced that involved mapping NMR spectra on a common chemical shift axis followed by interval-wisely applying the correlation optimized warping (COW) algorithm.

scholarly journals An ingenious method for the determination of the relative and absolute configurations of compounds containing aryl-glycerol fragments by 1H NMR spectroscopy

RSC Advances ◽  
2021 ◽  
Vol 11 (14) ◽  
pp. 8107-8116
Author(s):  
Xu Zhang ◽  
Kai-Zhou Lu ◽  
Hai-Wei Yan ◽  
Zi-Ming Feng ◽  
Ya-Nan Yang ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
H Nmr ◽  
Ingenious Method

A concise method was established to determine the relative and absolute configurations of aryl-glycerols that depend on the chemical shift differences (Δδ) of the diastereotopic methylene protons (H-3) by 1H NMR spectroscopy.

Asymetrical Dimer - allyl-palladiu Complexes II. Data from Infrared Spectra and Chemical Behaviour

2008 ◽  
Vol 59 (7) ◽  
Author(s):  
Maria Maganu ◽  
Filip Chiraleu ◽  
Constantin Draghici ◽  
Gheorghe Mihai
Keyword(s):  
Carbon Monoxide ◽  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Infrared Spectra ◽  
Analytical Methods ◽  
1H Nmr Spectroscopy ◽  
Chemical Behaviour ◽  
The Asymmetry ◽  
Pd Complexes

The previous data obtained by 1H-NMR spectroscopy established the existence of an asymmetry of the bond between Pd and p-allylic groups, even in the p-allyl-Pd complexes dimers which are considered usually symmetric dimers. The asymmetry of the bond depends by the substitutes of the allylic group. Other analytical methods were investigated for additional proof of the obtained results. Thus, this paper discusses how this asymmetry would be reflected in the infrared spectra and in the reaction of the complexes with carbon monoxide.

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