On the chemistry and high field nuclear magnetic resonance spectroscopy of rapamycin

1980 ◽  
Vol 58 (6) ◽  
pp. 579-590 ◽  
Author(s):  
John A. Findlay ◽  
Lajos Radics
Keyword(s):  
High Field ◽  
Nmr Spectra ◽  
Resonance Spectroscopy ◽  
X Ray ◽  
Conformational Isomers ◽  
H Nmr ◽  
Neutral Compounds ◽  
Complete Assignment ◽  
Hydrolysis Of ◽  
C Nmr

Base catalysed hydrolysis of rapamycin (C51H79NO13) affords six neutral compounds identified by chemical and spectroscopic means as 2a, 3b, 3d, 5, 2,4-dimethylphenol, and L(−)-piperidine-2-carboxylic acid 6, and whose generation has been plausibly rationalized. These findings as well as detailed analyses of 13C nmr and 1H nmr spectra provide independent corroboration of the X-ray derived rapamycin crystal structure 1. Structurally homogeneous in the solid state, rapamycin is found to occur in solutions as a mixture of two conformational isomers (approximately 4:1). Through nearly complete assignment of the high field 1H (400 MHz) and 13C (100.6 MHz) nmr spectra, the isomerism is shown to be associated with trans–cis rotation of an amidic bond within the 31-membered macrolide ring. The predominant form corresponds to the conformer portrayed by X-ray analysis.

E-Homolupane Derivatives Substituted in Position 17 and 22a. 1H NMR, 13C NMR and IR Spectra

1995 ◽  
Vol 60 (4) ◽  
pp. 619-635 ◽  
Author(s):  
Václav Křeček ◽  
Stanislav Hilgard ◽  
Miloš Buděšínský ◽  
Alois Vystrčil
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Coupling Constants ◽  
Side Chain ◽  
Oxidation Reactions ◽  
H Nmr ◽  
Complete Assignment ◽  
Nmr Techniques ◽  
Intramolecular Association ◽  
C Nmr

A series of derivatives with various oxygen functionalities in positions 17,22a or 19,20 was prepared from diene I and olefin XVI by addition and oxidation reactions. The structure of the obtained compounds was confirmed by 1H NMR, 13C NMR and IR spectroscopy. The kind of intramolecular association of the 17α-hydroxy group was studied in connection with modification of the side chain and substitution in position 22a. Complete assignment of the hydrogen signals and most of the coupling constants was accomplished using a combination of 1D and 2D NMR techniques. The 1H and 13C NMR spectra are discussed.

scholarly journals Reactions of 3-(p-substituted-phenyl)-5-chloromethyl-1,2,4-oxadiazoles with KCN leading to acetonitriles and alkanes via a non-reductive decyanation pathway

2018 ◽  
Vol 14 ◽  
pp. 3011-3017
Author(s):  
Akın Sağırlı ◽  
Yaşar Dürüst
Keyword(s):  
Nmr Spectra ◽  
2D Nmr ◽  
Synthetic Route ◽  
X Ray ◽  
H Nmr ◽  
2D Nmr Spectra ◽  
Tof Ms ◽  
C Nmr

The present work describes an unfamiliar reaction of 5-(chloromethyl)-3-substituted-phenyl-1,2,4-oxadiazoles with KCN affording trisubstituted 1,2,4-oxadiazol-5-ylacetonitriles and their parent alkanes, namely, 1,2,3-trisubstituted-1,2,4-oxadiazol-5-ylpropanes. To the best of our knowledge, the current synthetic route leading to decyanated products will be the first in terms of a decyanation process which allows the transformation of trisubstituted acetonitriles into alkanes by the incorporation of KCN with the association of in situ-formed HCN and most likely through the extrusion of cyanogen which could not be detected or isolated. In addition, the plausible mechanisms were proposed for both transformations. The structures of the title compounds were identified by means of IR, 1H NMR, 13C NMR, 2D NMR spectra, TOF–MS and X-ray measurements.

scholarly journals New Synthetic Routes for 1-Benzyl-1,4,7,10-tetraazacyclododecane and 1,4,7,10-Tetraazacyclododecane-1-acetic Acid Ethyl Ester, Important Starting Materials for Metal-coded DOTA-Based Affinity Tags

2007 ◽  
Vol 62 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Stephan W. Kohl ◽  
Katharina Kuse ◽  
Markus Hummert ◽  
Herbert Schumann ◽  
Clemens Mügge ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Ethyl Ester ◽  
Nmr Spectra ◽  
Acid Ethyl Ester ◽  
Affinity Tags ◽  
X Ray ◽  
H Nmr ◽  
Synthetic Routes ◽  
New Compounds ◽  
C Nmr

Two improved routes to synthesize 1-benzyl-1,4,7,10-tetraazacyclododecane (6) and 1,4,7,10- tetraazacyclododecane-1-acetic acid ethyl ester (11) are described as well as the synthesis of 1-{2-[4-(maleimido-N-propylacetamidobutyl)amino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane- 4,7,10-triacetic acid (17) and its Y, Ho, Tm, and Lu complexes. The 1H and 13C NMR spectra of the new compounds as well as the single crystal X-ray structure analyses of the intermediates 4-benzyl-1,7-bis(p-toluenesulfonyl)diethylenetriamine (3) and 1,4,7-tris(p-toluenesulfonyl)diethylenetriamine (7) are reported and discussed. The rare earth complexes of 17 have been characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry.

Kristallstruktur und spektroskopische Untersuchung von Mg(GeMe3)2 · 2 DME / Crystal Structure and Spectroscopic Study of Mg(GeMe3)2 · 2 DME

1984 ◽  
Vol 39 (7) ◽  
pp. 855-860 ◽  
Author(s):  
Lutz Rösch ◽  
Carl Krüger ◽  
A .-P. Chiang
Keyword(s):  
Crystal Structure ◽  
Spectroscopic Study ◽  
Nmr Spectra ◽  
X Ray ◽  
H Nmr ◽  
Magnesium Compound ◽  
C Nmr

Mg(GeMe3)2 · 2 DME is synthesized by reaction of Hg(GeMe3)2 with magnesium in 1 ,2 -- dimethoxyethane. The X-ray structure, IR, Raman, 1H NMR , and 13C NMR spectra of this first organogermyl magnesium compound are reported.

cis-Cyclohexano-9-crown-3 ether. Solid state and low-temperature solution stereochemistry as determined by X-ray crystallography and nuclear magnetic resonance spectroscopy

1993 ◽  
Vol 71 (7) ◽  
pp. 951-959 ◽  
Author(s):  
G.W. Buchanan ◽  
A.B. Driega ◽  
A. Moghimi ◽  
C. Bensimon ◽  
K. Bourque
Keyword(s):  
Low Temperature ◽  
Nmr Spectra ◽  
Solid Phase ◽  
Resonance Spectroscopy ◽  
Ring Inversion ◽  
X Ray ◽  
Common Features ◽  
X Ray Crystallography ◽  
Temperature Solution ◽  
C Nmr

The X-ray crystal structure of the title material has been determined at −130 °C. Low-temperature 1H1H COSY, 13C1H HETCOR, and DEPT 13C NMR spectra have been recorded, which permit unambiguous assignments of all carbon resonances when ring inversion is slow on the NMR timescale. The limiting low-temperature solution phase 13C spectrum has many common features with the solid phase 13C CPMAS spectrum recorded at 300 K. Spectra for the 7,10-tetra-deuterio derivative have also been obtained and substituent influences on 13C shieldings are discussed in detail.

X-Ray Structure Analysis and NMR Study of Sesquiterpene Lactone Hirsutolide

1995 ◽  
Vol 60 (2) ◽  
pp. 300-310 ◽  
Author(s):  
Urszula Rychłewska ◽  
Miloš Buděšínský ◽  
Halina Grabarczyk ◽  
Bohdan Drożdż ◽  
Miroslav Holub
Keyword(s):  
Crystal Structure ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Ring Conformation ◽  
X Ray ◽  
H Nmr ◽  
Nmr Study ◽  
Nmr Methods ◽  
The One ◽  
C Nmr

Hirsutolide, the C(8)-lactonized sesquiterpene of the heliangolide type has been studied by X-ray and NMR methods. In crystal the ten-membered ring conformation closely resembles the conformation observed in C(6)-lactonized heliangolides. This conformation, which can be described as a boat-chair is contrasted with the chair-chair conformation found in the crystals of other C(8)-lactonized heliangolide, scorpioidine. Broad signals in 1H and 13C NMR spectra indicated the conformation equilibrium in solution which was confirmed by observation of signals of two conformers (ca 3 : 1) in low temperature 1H NMR spectra. The major conformer is the one present in the crystal structure of hirsutolide and the minor conformer corresponds very likely to the one observed in the crystal structure of scorpioidine.

Sterically Crowded Heterocycles. I. Molecular Structure of 3-Chain Substituted 2-Phenylimidazo[1,2-a]pyridinium Salts

1994 ◽  
Vol 59 (12) ◽  
pp. 2677-2690 ◽  
Author(s):  
Stanislav Böhm ◽  
Richard Kubík ◽  
Martin Hradilek ◽  
Jan Němeček ◽  
Michal Hušák ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Nmr Spectra ◽  
Molecular Structures ◽  
Pyridinium Salts ◽  
Protonation Site ◽  
X Ray ◽  
H Nmr ◽  
C Nmr ◽  
Pyridinium Perchlorate

2-Phenyl-3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridine (I) was converted to corresponding 1-alkyl-2-phenyl-3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridinium salts III - VI and 2-phenyl- 3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridinium perchlorate (VII). The protonation site is discussed in terms of calculated molecular energies of alternative cations. The X-ray structure analyses of enone I and its quaternary periodide III are reported and compared with the PM3 molecular optimizations. 1H NMR and 13C NMR spectra reveal well changes of molecular structures caused by the transformation of the base I into salts III - VII.

scholarly journals Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds

2020 ◽  
Vol 16 ◽  
pp. 190-199
Author(s):  
Vuyisa Mzozoyana ◽  
Fanie R van Heerden ◽  
Craig Grimmer
Keyword(s):  
Single Crystal ◽  
Phenyl Ring ◽  
Fluorine Atom ◽  
Nmr Spectra ◽  
Intramolecular Interaction ◽  
X Ray ◽  
Solution State ◽  
H Nmr ◽  
Mild Conditions ◽  
C Nmr

4-(2-Fluorophenyl)-7-methoxycoumarin (6) was synthesized by Pechmann reaction under mild conditions via a three-step reaction. The solution-state 1H NMR spectra of 6 showed a strong intramolecular interaction between F and H5 (J FH = 2.6 Hz) and 13C NMR suggested that this C–F···H–C coupling is a through-space interaction. The 2D 19F-{1H} HOESY and 1H-{19F} 1D experiments were done to confirm this F···H interaction. The single crystal X-ray structure and the DFT-optimized structure showed that the fluorinated phenyl ring favors the orientation with the fluorine atom closer to H5 than H3. The X-ray structure also showed the existence of the intermolecular C–F···H–C interaction.

scholarly journals Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C-F…H-C bond

2019 ◽  
Author(s):  
Vuyisa Mzozoyana ◽  
Fanie R van Heerden ◽  
Craig Grimmer
Keyword(s):  
Single Crystal ◽  
Phenyl Ring ◽  
Fluorine Atom ◽  
Nmr Spectra ◽  
Intramolecular Interaction ◽  
X Ray ◽  
Solution State ◽  
H Nmr ◽  
Mild Conditions ◽  
C Nmr

4-(2-fluorophenyl)-7-methoxycoumarin (6) was synthesized by Pechmann reaction under mild conditions via a three step-reaction. The solution-state 1H NMR spectra of 6 showed a strong intramolecular interaction between F and H5 (J FH = 2.6 Hz) and 13C NMR suggested that this C-F…H-C coupling is a through-space interaction. The 2‑D HOESY spectrum and 1H‑{19F} 1‑D spectrum were also done to confirm this F…H interaction. The single crystal X-ray structure and the DFT-optimized structure showed that the fluorinated phenyl ring favours the orientation with the fluorine atom is closer to H5 than H3. The X-ray structure also showed the existence of the intermolecular C-F…H-C interactions.

Hydrolyse des dérivés de cyclopropylidène-3 propyle. Structure et stéréochimie des alcools précurseurs et des produits résultant de l'hydrolyse

1981 ◽  
Vol 59 (7) ◽  
pp. 1089-1095 ◽  
Author(s):  
Robert Faure ◽  
Gilbert Leandri ◽  
Alain Meou
Keyword(s):  
Ir Spectroscopy ◽  
Nmr Spectra ◽  
Molecular Conformation ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
H Nmr ◽  
Hydrolysis Products ◽  
Hydrolysis Of ◽  
C Nmr

The 13C nmr spectra of 14 β-cyclopropylidenic alcohols 1 have been determined:[Formula: see text]All the chemical shifts were assigned and the substituent effects are discussed as a function of molecular conformation. The stereochemistry of two diastereoisomers of alcohols 1e (R1 = R3 = H; R2 = R4 = CH3) and 1k (R3 = H; R1 = R2 = R4 = CH3) was established from ir spectroscopy and 1H nmr results.The 13C nmr spectra of products arising from hydrolysis of 3-cyclopropylidene propanol 1a and 4-cyclopropylidene 2-butanol 1b tosylates have been also recorded. The analysis of these data enables us to establish unambiguously the structure and the stereochemistry of the hydrolysis products.

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