scholarly journals Function-oriented investigations of a peptide-based catalyst that mediates enantioselective allylic alcohol epoxidation.

2014 ◽  
Vol 5 (11) ◽  
pp. 4504-4511 ◽  
Author(s):  
Nadia C. Abascal ◽  
Phillip A. Lichtor ◽  
Michael W. Giuliano ◽  
Scott J. Miller
Keyword(s):  
Allylic Alcohol ◽  
Nmr Data ◽  
Peptide Catalyst

Experimentally derived analysis of selectivity of a peptide catalyst through study of substrate scope, kinetics, catalyst analogues, and NMR data.

Recombination of Optically Excited Carriers in a-Si:H at Low temperatures and Intermediate Times

2002 ◽  
Vol 715 ◽  
Author(s):  
J. Whitaker ◽  
T. Su ◽  
P. C. Taylor
Keyword(s):  
Electron Spin Resonance ◽  
Low Temperatures ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Dipolar Relaxation ◽  
Spin Lattice ◽  
Carrier Recombination ◽  
Nmr Data ◽  
Spin Resonance ◽  
Time Regime

AbstractOptically induced electron spin resonance (LESR) studies on time scales in between the previously published PL and LESR results (approximately 10 ms to 10 s) allow one to examine the cross over between energy-loss (downward) hopping of carriers and carrier recombination via tunneling. In addition, data in this time regime are directly compared in the same sample with NMR data on the dipolar spin-lattice relaxation of the bonded hydrogen where light induced electrons and holes are responsible for dipolar relaxation of bonded hydrogen. The LESR results confirm the interpretation of the NMR measurements.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

Synthesis of the C19–C30 Bis-THF Fragment of Iriomoteolide-13a via Stepwise SN2 Cyclization and Intramolecular syn-Oxypalladation

2020 ◽  
Author(s):  
Hui Zhao ◽  
Kai Gao ◽  
Haichen Ma ◽  
Tsz Chun Yip ◽  
Wei-Min Dai
Keyword(s):  
Aldol Reaction ◽  
Allylic Alcohol ◽  
Asymmetric Dihydroxylation ◽  
Hydroxy Groups

The C19–C30 bis-THF fragment of the proposed structure of iriomoteolide-13a has been synthesized. The w-mesyloxy-substituted stereotetrad possessing three continuous hydroxy groups was generated by <i>anti</i>-aldol reaction and asymmetric dihydroxylation (AD). Upon heating in pyridine the stereotetrad underwent an S<sub>N</sub>2 cyclization to form the C19–C22 THF ring. It was followed by an intramolecular <i>syn</i>-oxypalladation of the C28 chiral allylic alcohol to give the C23–C26 THF ring.

Unexpected Keto-enol Tautomerism in the Cyclopyridinophane Class Direct and indirect proofs

2008 ◽  
Vol 59 (10) ◽  
Author(s):  
Paul Ionut Dron ◽  
Neculai Doru Miron ◽  
Gheorghe Surpateanu
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Stable Conformer ◽  
Ph Measurements ◽  
Theoretical Methods ◽  
Nmr Data ◽  
Tautomeric Forms ◽  
New Compounds

The paper presents the synthesis of cyclo (bis-paraquat p-phenylene p-phenylene-carbonyl) tetrakis (hexafluorophosphate), named �CETOBOX�, and the closely related structural determinations. This compound exists in three tautomeric forms. These forms were evidentiated by NMR-data (1H-NMR, TOCSY, COSY, NOESY), UV-Vis spectra coupled with pH measurements and by synthesis. As the �CETOBOX� gives �in situ� only the corresponding monoylide, the synthesis of a new fluorescent indolizine cyclophane has been performed by a 3+2 cycloaddition. All structures of the new compounds presented herein have been established by NMR spectroscopy. Also, theoretical methods (MM3, AM1, AM1-COSMO and B88LYPDFT) have been used to determine the most stable conformer structures.

Glucan isolated from leaves of Althaea officinalis L.

1983 ◽  
Vol 48 (7) ◽  
pp. 2082-2087 ◽  
Author(s):  
Alžbeta Kardošová ◽  
Jozef Rosík ◽  
Rudolf Toman ◽  
Peter Capek
Keyword(s):  
Medicinal Plant ◽  
Periodate Oxidation ◽  
Linear Structure ◽  
Water Soluble ◽  
Partial Hydrolysis ◽  
Methylation Analysis ◽  
Glycosidic Bonds ◽  
Nmr Data ◽  
Althaea Officinalis ◽  
C Nmr

A water-soluble low-molecular D-glucan was isolated from leaves of the medicinal plant marsh-mallow (Althaea officinalis L.). The results of methylation analysis, partial hydrolysis, periodate oxidation, and 13C NMR data indicated a virtually linear structure with α-(1→6) glycosidic bonds.

Synthesis and characteristics of ethylenediamine-N,N'-di-S-α-isovalerate and isomers of its cobalt(III) complexes

1982 ◽  
Vol 47 (1) ◽  
pp. 210-216 ◽  
Author(s):  
Milan Strašák ◽  
František Bachratý ◽  
Jaroslav Majer
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Chemical Parameters ◽  
Methyl Group ◽  
Nmr Data ◽  
Physico Chemical ◽  
Natural Amino Acids ◽  
C Nmr

The synthesis and physico-chemical parameters are described of a new complexone based on natural amino acids, viz. ethylenediamine-N,N'-di-S-α-isovalerate (SS-EDDIV). 1H- and 13C-NMR data revealed that the methyl group in the substance are not equivalent. The isomers of the cobalt(III) complex with the asymmetric tetradentate SS-EDDIV ligand were prepared and separated; their characteristics are given. The absolute configuration of two of the five theoretically feasible isomers was determined based on their electronic absorption spectra and circular dichroism data.

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