A route to 24-epibrassinolide from ergosterol avoiding the use of osmium tetroxide

1990 ◽  
Vol 55 (11) ◽  
pp. 2738-2755 ◽  
Author(s):  
Václav Černý ◽  
Miloš Buděšínský
Keyword(s):  
Nmr Spectra ◽  
Osmium Tetroxide ◽  
Model Compound ◽  
Side Chain ◽  
C Nmr

A synthesis of (22R,23R)-2α,3α,22,23-tetrahydroxy-5α-ergostan-6-one (V) from the dienone IV via the diepoxide XXII is described. The tetrol V is a key intermediate in the synthesis of 24-epibrassinolide. The reactivity of the side chain was studied on 5α-ergost-22-en-6-one (XIV) as a model compound. 1H and 13C NMR spectra of 24-epibrassinolide derivatives are discussed.

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.

Estimation of the stereoselectivity of reduction of 3,3,5,5-tetramethylcyclohexanone by sodium borohydride

1976 ◽  
Vol 54 (22) ◽  
pp. 3536-3540 ◽  
Author(s):  
Donald C. Wigfield ◽  
Gerald W. Buchanan ◽  
Catherine A. Ashley ◽  
Steve Feiner
Keyword(s):  
Raney Nickel ◽  
Sodium Borohydride ◽  
Nmr Spectra ◽  
Model Compound ◽  
Hydroxyl Group ◽  
Product Ratio ◽  
Major Isomer ◽  
C Nmr ◽  
Hydroxyethyl Group

4-(1-Hydroxyethyl)-3,3,5,5-tetramethylcyclohexanone has been prepared to serve as a model for 3,3,5,5-tetramethylcyclohexanone on which the reduction stereochemical product ratio may be experimentally determined. Reduction with sodium borohydride in 2-propanol gives two epimers in a 95.5:4.5 ratio. The major isomer is shown to be the less stable by equilibration over Raney nickel. Proton and 13C nmr spectra confirm that this major epimer is cis-4-(1-hydroxyethyl)-3,3,5,5-tetramethylcyclohexanol and show that this compound exists predominantly in the conformation with an axial hydroxyethyl group and an equatorial hydroxyl group. It is concluded that reduction of this model compound proceeds at least 95.5% by equatorial attack.

scholarly journals 1H and 13C NMR Spectral Studies on N-(j, k-Dichlorophenyl)- and N-(j, k-Dimethylphenyl)-acetamides and Substituted Acetamides

2007 ◽  
Vol 62 (1-2) ◽  
pp. 84-90 ◽  
Author(s):  
Shilpa Gowda ◽  
Basavalinganadoddy Thimme Gowda
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spectral Studies ◽  
Side Chain ◽  
Aryl Group ◽  
1H And 13C Nmr ◽  
Methyl Substitution ◽  
Methods Of Calculation ◽  
Experimental Values ◽  
C Nmr

70 N-( j,k-Dichlorophenyl / j,k-dimethylphenyl)-acetamides and substituted acetamides of the general formula j,k-X′2C6H3NH-CO-CH3−iXi ( j,k = 2,3; 2,4; 2,5; 3,4 or 3,5; X, X′ = Cl or CH3; i = 0, 1, 2 or 3) have been synthesized and their 1H and 13C NMR spectra in solution were studied. The influence of Cl and methyl substitution in the side chain as well as in the aryl group was ystematically investigated and discussed in detail. Chemical shifts of all aromatic protons and carbon atoms were computed by adding the substituent contributions in three different ways to those of the unsubstituted molecules. The agreement with the experimental values is discussed in detail for the three different methods of calculation.

Hindered Rotation in Poly(N-acyl)iminoalkylenes - A 13C Nuclear Magnetic Resonance Study

1995 ◽  
Vol 50 (9) ◽  
pp. 1404-1411 ◽  
Author(s):  
Bernabé L. Rivas ◽  
Klaus Albert ◽  
Kurt E. Geckeler ◽  
Ernst Bayer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Cationic Polymerization ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Side Chain ◽  
Magnetic Resonance Study ◽  
Hindered Rotation ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr

AbstractPoly(N-acetyl)iminoethylene. poly(N-propionyl)iminoethylene and poly(N-acetyl)-2,2-dimethyliminoethylene were prepared by cationic polymerization in solution of 2-methyl- 2-oxazoline, 2-ethyl-2-oxazoline, and 2,4,4-trimethyl-2-oxazoline respectively. The 13C NMR spectra of the polymers obtained showed different sets of shifts for the carbon atoms of the backbone as well as for the N-acylimino side chain due to the restricted rotation of the Nacylimino group. The temperature dependence of the N-acylimino side chain signals showed a different coalescence behaviour depending on the substituents at both the main and the side chain.

Conformational structure of ethylene glycol dibenzoate. Vibrational and NMR spectra

1981 ◽  
Vol 46 (8) ◽  
pp. 1913-1929 ◽  
Author(s):  
Bohdan Schneider ◽  
Pavel Sedláček ◽  
Jan Štokr ◽  
Danica Doskočilová ◽  
Jan Lövy
Keyword(s):  
Ethylene Glycol ◽  
Vibrational Spectra ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Conformational Structure ◽  
Infrared And Raman Spectra ◽  
H Nmr ◽  
Liquid States ◽  
Crystalline Forms ◽  
C Nmr

It was found that three crystalline forms of ethylene glycol dibenzoate can be prepared. Infrared and Raman spectra of these three forms, as well as of the glassy and liquid states, were measured. From 3JHH coupling constants obtained by analysis of the 13C satellite band of the -CH2- group in 1H NMR spectra, and from the 3JCH coupling constants of the -CO.O.CH2- fragment obtained by analysis of the carbonyl band in 13C NMR spectra it was found that in the liquid state the -CH2-CH2- group exists predominantly in the gauche conformational structure, and the bonds C-O-C-C assume predominantly a trans orientation. The results of the analysis of NMR and vibrational spectra were used for the structural interpretation of conformationally sensitive bands in vibrational spectra of ethylene glycol dibenzoate.

13C NMR spectra of 1-aryl-ferrocenylethylenes

1986 ◽  
Vol 51 (3) ◽  
pp. 670-676 ◽  
Author(s):  
Eva Solčániová ◽  
Štefan Toma ◽  
Tibor Liptaj
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
13C Nmr Spectra ◽  
Bridge Group ◽  
C Nmr ◽  
Electron Effects

13C NMR spectra of 18 ferrocene analogues of trans stilbenes (1-aryl-2-ferrocenylethylenes) were measured. It was found that bridge group weakens the transfer of the substituent electron effects into ferrocene nucleus, especially distinctly into 3',4'positions of cyclopentadienyl ring. The transfer of substituent effects into β-position of the bridge -CH=CH- is greater in derivatives studied by us than in stilbenes. Synthesis of 1-(4-dimethylaminophenyl)-2-ferrocenylethylene is described.

The synthesis and stereochemistry of the ternary cobalt(III) complex with a stereospecific ligand derived from (S)-leucine

1986 ◽  
Vol 51 (2) ◽  
pp. 318-326 ◽  
Author(s):  
Milan Strašák ◽  
Pavol Novomeský
Keyword(s):  
Ir Spectroscopy ◽  
Aqueous Medium ◽  
Absorption Spectroscopy ◽  
Absolute Configuration ◽  
Nmr Spectra ◽  
Methyl Groups ◽  
Electron Absorption Spectroscopy ◽  
Electron Absorption ◽  
C Nmr

A new stereospecific ligand, ethylenediamine-N,N'-di(S)-α-isocapronic acid, was synthesized by condensation of (S)-leucine with 1,2-dibromoethane in alkaline aqueous medium. It follows from the 1H and 13C NMR spectra that the terminal methyl groups are chemically and magnetically nonequivalent. Of the four theoretically possible isomers of the ternary cobalt (III) complex with ethylenediamine, separation on catex yielded only one, whose absolute configuration was determined by a combination of 1H and 13C NMR, electron absorption spectroscopy and CD and IR spectroscopy.

17O and 13C NMR spectra of some geminal diacetates

1988 ◽  
Vol 53 (3) ◽  
pp. 588-592 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Jaroslav Holeček
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
The Other ◽  
13C Nmr Spectra ◽  
Other Hand ◽  
Carboxylic Esters ◽  
C Nmr ◽  
Oxygen Atoms

The 17O and 13C NMR spectra of eight geminal diacetates RCH(O(CO)CH3)2 derived from simple aldehydes have been measured. In contrast to the dicarboxylates R1R2E(O(CO)R3)2, where E = Si, Ge, or Sn, whose 17O NMR spectra only contain a single signal, and, on the other hand, in accordance with organic carboxylic esters, the 17O NMR spectra of the compound group studied always exhibit two well-resolved signals with the chemical shifts δ(17O) in the regions of 183-219 ppm and 369-381 ppm for the oxygen atoms in the groups C-O and C=O, respectively.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

Synthesis of the six isomeric thieno[c]-fused 1,5- and 1,6-naphthyridines

1991 ◽  
Vol 56 (11) ◽  
pp. 2340-2351 ◽  
Author(s):  
Salo Gronowitz ◽  
Johan Malm ◽  
Anna-Britta Hörnfeldt
Keyword(s):  
Nmr Spectra ◽  
Coupling Reaction ◽  
One Pot ◽  
C Nmr

trough the use of Pd(0)-catalyzed coupling between 2- and 4-formyl-3-thiopheneboronic acids and 3-amino-2-bromopyridine and 4-acetamido-3-bromopyridine, convenient one-pot procedures for the preparation of thieno[2,3-c]-1,5-naphthyridine, thieno[3,4-c]-1,5-naphthyridine, thieno-[2,3-c]-1,6-naphthyridine, and thieno[3,4-c]-1,6-naphthyridine have been developed. In order to obtain thieno[3,2-c]-1,6-naphthyridine 2-(tributylstannyl)-3-thiophene aldehyde had to be used, since the organometallic partner in the coupling reaction, 3-formyl-2-thipheneboronic acid, is too easily deboronated. The effect of silver(I) oxide and thallium(I) carbonate on the coupling was studied. 1H and 13C NMR spectra of the six isomeric thieno{c]-fused 1,5- and 1,6-naphthyridines are discussed.

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