scholarly journals Eu(fod)3 EFFECT ON 1H NMR SPECTRA OF 3-ARYLISOCOUMARINS AND 3-ARYL-3,4-DIHYDROISOCOUMARINS WITH ALKOXY, ESTER AND AMIDE GROUPS

2017 ◽  
pp. 74-80
Author(s):  
V. Khilya ◽  
O. Shablykina ◽  
M. Tsapko ◽  
S. Shilin ◽  
V. Moskvina ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Methyl Ester ◽  
Oxygen Atom ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Shift Reagent ◽  
1H Nmr Spectra ◽  
Aromatic Substituent ◽  
Phenoxy Acetic Acid ◽  
Hydroxyacetic Acid

The effect of the lanthanide shift reagent (LSR) – tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octa-dionate) of Europium – Eu(fod)3 – on 1H NMR spectra of functionalized 3-arylisocoumarins and 3-aryl-3,4-dihydroisocoumarins was investigated. Based on previous studies of LSR interactions with benzopyrones, it was expected that the main coordination centre for the Eu3+ would be the exocyclic Oxygen atom of the heterocycle, but the possibility of competition from aromatic substituent functional groups was also considered. By measuring lanthanide-induced shifts (LIS) of the proton signals of the molecules at different ratios of substrate and Eu(fod)3, specific LIS values were determined. Based on those, it was concluded that the main direction of LSR coordination with 3-(2-hydroxy-5-methylphenyl)-1Hisochromen-1-one, 3-(2-methoxy-5-methylphenyl)-1H-isochromen-1-one and 3-(2-methoxy-5-methylphenyl)isochroman-1-one is the exocyclic Oxygen atom of the heterocycle, because the maximum LIS were recorded for the H-8 atom of isochromone system of these derivatives. In the case of ethyl ester of [2-(4-(1-oxo-1H-isochromen-3-yl)phenoxy] acetic acid and methyl ester of [2-(4-(1-oxoisochroman-3-yl)phenoxy]acetic acid comparable LIS values were observed both for H-8 and for the methylene group of the hydroxyacetic acid fragment, therefore, in such molecules the coordination of the Eu3+ to the heterocycle or to the aliphatic ester group is almost equally probable. In spectrum of methyl ester of N-{[4-(1-oxo-1H-isochromen-3-yl)phenoxy]acetyl}valine and N-{[4-(1-oxoisochroman-3-yl)-phenoxy]acetyl}valine there are insignificant LIS of H-8; and the maximum LIS were observed for the signals of the protons neighboring the two carbonyl groups of hydroxyacetic acid and valine fragments. Thus, these compounds interact w

Proximity effects in 29Si, 13C, and 1H NMR spectra of ortho substituted phenoxytrimethylsilanes

1990 ◽  
Vol 55 (8) ◽  
pp. 2019-2026 ◽  
Author(s):  
Jan Schraml ◽  
Václav Chvalovský ◽  
Harald Jancke ◽  
Peter Koehler ◽  
Mikhail F. Larin ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
1H Nmr ◽  
Proximity Effect ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Proximity Effects ◽  
1H Nmr Spectra ◽  
Methyl Groups ◽  
Conformational Preferences

NMR Spectra of eight ortho substituted phenoxytrimethylsilanes, 2-X-C6H4-OSi(CH3)3 (X = Cl, Br, OCH3, NH2, NO2, OSi(CH3)3, CH3, and H), are reported. In contrast to analogous ortho substituted methoxybenzenes the 13C chemical shifts of C-2 and C-6 aromatic carbons do not exhibit consistent trends indicating different conformational preferences in the trimethylsiloxybenzenes. Under the influence of the ortho substituents the nuclei of OSi(CH3)3 group (29Si, 13C, and 1H) are deshielded; compounds with X = CH3 (and H) appear anomalous in this respect. It is argued that this proximity effect is not due to an interaction involving terminal methyl groups but involves the oxygen atom of the OSi(CH3)3 group; it is most likely due to an interaction with unshared electrons of the ortho substituent.

SYNTHESIS, CHARACTERISATION AND ANTIFUNGAL ACTIVITYOF SOME NEWLY SYNTHESISED POLYSUBSTITUTED PYRAZOLES

INDIAN DRUGS ◽  
2017 ◽  
Vol 54 (10) ◽  
pp. 23-29
Author(s):  
A. Kumar ◽  
◽  
C. P. Singh
Keyword(s):  
Acetic Acid ◽  
Biological Activity ◽  
Antifungal Activity ◽  
Formic Acid ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Acid Hydrazide ◽  
1H Nmr Spectra ◽  
Aryl Aldehyde

A novel series of polysubstituted pyrazoles were synthesised by the cyclization of (α phenoxy/octyl) acetyl aryl hydrazones in presence of formic acid, by refluxing (α-phenoxy/octyl) acetic acid hydrazide and substituted aryl aldehyde, using C2H5OH as solvent. The newly synthesised compounds were characterised by IR, 1H NMR spectra and also screened for their promising biological activity i.e. antifungal activity.

Isolation of (23R) 3α, 7α,23-trihydroxy-5β-cholan-24-oic (β-phocaecholic) acid from duck bile. 1H NMR spectra of its derivatives

1986 ◽  
Vol 51 (8) ◽  
pp. 1722-1730 ◽  
Author(s):  
Jiří Klinot ◽  
Milan Jirsa ◽  
Eva Klinotová ◽  
Karel Ubik ◽  
Jiří Protiva
Keyword(s):  
Bile Acid ◽  
Methyl Ester ◽  
1H Nmr ◽  
Marine Mammals ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Methyl Groups ◽  
H Nmr ◽  
Derivatives Of

(23R) 3α, 7α,23-Trihydroxy-5β-cholan-24-oic acid (IV) - a bile acid typical of some marine mammals - was now isolated from duck bile. Acid IV was characterized as derivatives V - VIII, XI and XII and oxidatively degraded to derivatives of 24-nor-5β-cholan-23-oic acid, XIII - XVIII. The 1H NMR spectra of these compounds and (23S) methyl ester X are discussed and the effect of substitution in position 23 on the chemical shifts of the methyl groups is summarized.

scholarly journals Convenient approaches to the synthesis of 6-amino- and 6-oxoimidazo[4,5-b]pyrazolo[3,4-e]pyridines

2021 ◽  
Vol 19 (1(73)) ◽  
pp. 10-15
Author(s):  
G. G. Yakovenko ◽  
M. V. Vovk
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Ir Spectra ◽  
Carboxylic Acids ◽  
1H Nmr ◽  
Nmr Spectra ◽  
1H Nmr Spectra ◽  
Biologically Active ◽  
Spectral Measurements ◽  
Absorption Bands

Aim. To develop convenient approaches to the synthesis of 6-amino- and 6-oxoimidazo[4,5-b]pyrazolo[3,4-e]pyridines as promising biologically active scaffolds.Results and discussion. It has been found that cyclocondensation of N-Boc-4-aminopyrazole-5-carbaldehydes with creatinine can be used as an effective method for obtaining 6-aminoimidazo[4,5-b]pyrazolo[3,4-e]pyridines previously unknown. For the synthesis of their 6-oxoanalogs, the reaction of 5-aminopyrazolo[4,3-b]pyridine-6-carboxylic acids used in a modifed Curtius rearrangement with diphenylphosphorylazide was successful. This method was implemented through the stage of the intermediate aminoisocyanates formation.Experimental part. The reaction of N-Boc-4-aminopyrazole-5-carbaldehydes with creatinine in the presence of pyrrolidine as a catalyst in refluxing acetic acid allowed to obtain 6-aminoimidazo[4,5-b]pirazolo[3,4-e]pyridines with the yields of 54 – 70 %. The structure of the compounds synthesized was proven by spectral measurements. In the 1H NMR spectra there were singlets of H-3 (7.63 – 7.88 ppm) and H-8 (7.87 – 8.26 ppm) protons, as well as broad singlets of the NH2 group in the range of 7.05 – 7.21 ppm. Heating of 5-aminopyrazolo[4,3-b]pyridine-6-carboxylic acids with triethylamine and diphenylphosphorylazide in dioxane for 6 hours gave 1-substituted imidazo[4,5-b]pyrazolo[3,4-е]pyridine-6(5Н)-ones with the yields of 67 – 80 %. The IR-spectra of the compounds synthesized were characterized by the absorption bands of the C=O (1705 – 1708 cm-1) and NH (3275 – 3281 cm-1) groups. 1H NMR-spectra were characterized by singlets of H-3 and H-8 protons in the intervals of 7.43 – 8.08 ppm and 7.92 – 8.32 ppm respectively, as well as by two broad singlets of NH-protons in the ranges of 10.90 – 11.12 ppm and 11.25 – 11.37 ppm.Conclusions. Effective approaches to the synthesis of new promising heterocyclic systems of 6-amino- and6-oxoimidazo[4,5-b]pirazolo[3,4-e]pyridines have been developed. Cyclocondensations of N-Boc-4-aminopyrazole-5-carbaldehydes with creatinine and 5-aminopyrazolo[4,3-b]pyridine-6-carboxylic acids with diphenylphosphorylazide have been proven to be convenient ways to obtain these compounds with good yields.Key words: N-Boc-4-aminopyrazole-5-carbaldehyde; creatinine; 5-aminopyrazolo[4,3-b]pyridine-6-carboxylic acid; diphenylphosphorylazide; 6-amino(oxo)imidazo[4,5-b]pyrazolo[3,4-e]pyridines;cyclocondensation

29Si, 13C and 1H NMR spectra of some trimethylsiloxy- and bis(trimethylsiloxy)butene isomers

1983 ◽  
Vol 48 (11) ◽  
pp. 3097-3103 ◽  
Author(s):  
Jan Schraml ◽  
Ján Šraga ◽  
Pavel Hrnčiar
Keyword(s):  
Double Bond ◽  
Nmr Spectroscopy ◽  
Oxygen Atom ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Trimethylsilyl Group ◽  
H Nmr ◽  
Steric Crowding

Three isomers of trimethylsiloxybutene were prepared and identified by 1H NMR spectroscopy to be 2-trimethylsiloxy-1-butene and E and Z 2-trimethylsiloxy-2-butenes. E and Z isomers of 2,3-bis(trimethylsiloxy-2-butene were also prepared. 29Si and 13C chemical shifts in these compounds are interpreted. The shifts indicate that the spatial arrangements in the CH3-C-O-Si(CH3)3 fragment is the same in all the pertinent compounds. Steric crowding forces the trimethylsilyl group to assume conformations in which conjugation between unshared electrons of oxygen atom and the electrons of the double bond is inhibited. As a result, olefinic β carbons are deshielded and the shielding of the silicon is increased.

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