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.

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.

Nuclear Magnetic Resonance Studies on Aromatic Compounds, IV 13C NMR Spectra of Some Disulpho-substituted 1- and 2-Naphthols

1977 ◽  
Vol 32 (7) ◽  
pp. 818-820 ◽  
Author(s):  
Kauko Räisänen ◽  
Lauri H. J. Lajunen
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Compounds ◽  
Nmr Spectra ◽  
Hydroxyl Group ◽  
Mesomeric Effect ◽  
13C Nmr Spectra ◽  
Magnetic Resonance Studies ◽  
Fine Splitting ◽  
Substituted 1 ◽  
C Nmr

The 13C NMR spectra of 1-hydroxynaphthalene-3,6-disulphonic, 1-hydroxynaphthalene- 3,8-disulphonic, 2-hydroxynaphthalene-3,6-disulphonic, and 2-hydroxynaphthalene-6,8-disulphonic acids were determined with and without noise-decoupling. The fine splitting caused by the long-range couplings pattern was used in the identification of the resonances lines of the 13C nuclei. The combined influence of the mesomeric effect of the hydroxyl group and that of the sulphonate groups have been discussed.

Reactions of N-substituted 2-aminopyridines with chloroacetyl chloride; Formation of a new series of heterocyclic betaines: 1-Substituted 4-chloromethyl-2-oxopyrido[1,2-a]pyrimidin-5-ium-3-olates

1989 ◽  
Vol 54 (5) ◽  
pp. 1376-1387 ◽  
Author(s):  
Hana Hulinská ◽  
Miloš Buděšínský ◽  
Jiří Holubek ◽  
Oluše Matoušová ◽  
Hana Frycová ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Sodium Borohydride ◽  
Nmr Spectra ◽  
Aqueous Ethanol ◽  
Hydrogen Bromide ◽  
Chloroacetyl Chloride ◽  
Gastric Lesions ◽  
Substitution Reactions ◽  
Reaction Compound ◽  
C Nmr

N-(2-Pyridyl)-2-chloroacetamide reacted with 1-methylpiperazine and gave the expected compound III. Attempts at preparing the N-substituted N-(2-pyridyl)-2-chloroacetamides by reactions of N-substituted 2-aminopyridines with chloroacetyl chloride in benzene in the presence of N,N-dimethylacetamide were negative and took an unexpected course. 2-Anilinopyridine and 2-(cyclohexylamino)pyridine afforded compounds which were identified by 1H and 13C NMR spectra as the heterocyclic betaines IVa and IVb. 2-(1-Butylamino)pyridine, 2-(benzylamino)pyridine and 2-(2-phenylethylamino)pyridine gave similarly compounds IVc-IVe. The chloromethyl compounds IVa-IVe underwent normal substitution reactions with 1-methylpiperazine and gave the methylpiperazino compounds Va-Ve. Attempts to reduce the betaines with sodium borohydride in aqueous ethanol proceeded in one case as the hydrogenolytic displacement of the chlorine atom with hydrogen (product VIa), in another case as ethanolysis (product VIIb). Formation of VIb by treatment of IVb with hydrogen bromide in boiling acetic acid is probably the result of a disproportionation reaction. Compound III (dimaleate VÚFB-17 103) was practically equipotent with pirenzepine (I) as an anti-ulcer agent in the test of indomethacine-induced gastric lesions in rats but was much weaker in tests for antocholinergic and antisecretory activity.

Anhydrobetulin and its derivatives

1991 ◽  
Vol 56 (4) ◽  
pp. 886-904 ◽  
Author(s):  
Alois Vystrčil ◽  
Václav Křeček ◽  
Jiří Protiva ◽  
Miloš Buděšínský
Keyword(s):  
Double Bond ◽  
Alkaline Medium ◽  
Sodium Borohydride ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Cotton Effect ◽  
Addition Reactions ◽  
Chemical Transformations ◽  
C Nmr ◽  
Reduction Of Ketones

The structure of anhydrobetulin II and its derivatives I, III and IV has been solved using 1H and 13C NMR spectra, mass spectra and chemical transformations. It has been proven that in addition reactions the trisubstituted double bond is attacked selectively from the α-side under formation of D/E cis-annelated derivatives VIII, X and XI. The 22-oxo derivative XIII exhibits an anomalous Cotton effect and, in contrast to its saturated analogue XXVII,it is not epimerized in alkaline medium. Trinordiketone XXI easily epimerizes to a mixture in which the 17βH-epimer XXIb predominates, trinorketone XXIV is stable only if the annelation of rings D and E is trans. These differences are explained in terms of steric interactions of substituents in position 19. The steric course of reduction of ketones XIII and XXIV with sodium borohydride is described.

Preparation of C(18)-empiric 20,29,30-trinorlupane derivatives. 1H, 13C NMR and mass spectra

1986 ◽  
Vol 51 (3) ◽  
pp. 621-635 ◽  
Author(s):  
Václav Křeček ◽  
Jiří Protiva ◽  
Miloš Buděšínský ◽  
Eva Klinotová ◽  
Alois Vystrčil
Keyword(s):  
Nitrous Acid ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Allylic Oxidation ◽  
Hydroxyl Group ◽  
Methyl Groups ◽  
Unsaturated Ketone ◽  
H Nmr ◽  
C Nmr

Reaction of amide I with nitrous acid gave the olefins II, III and IV. On allylic oxidation of olefin IV α,β-unsaturated ketone V is formed from which olefins VIII and IX were prepared by a sequence of further reactions. Addition of hydrogen to the double bond of olefin IV and α,β-unsaturated ketone V takes place on catalytic hydrogenation from the β-side and leads to derivatives with cis-annellated rings D/E. This made the preparation of hydrocarbons VI and VII epimeric on C(18) possible, which represent reference compounds for the study of the effect of substituents on the chemical shifts of the methyl groups and the saturated carbon atoms of 18αH and 18βH-lupane derivatives. The configuration of the hydroxyl group in epimers XI and XII were derived from 1H NMR spectra. Deuteration of olefins III, IV and IX gave deuteriohydrocarbons XVI to XVIII. The 1H, 13C NMR and mass spectra of the substances prepared are discussed.

scholarly journals 13C nuclear magnetic resonance studies. 64. The 13C spectra of a variety of bicyclo[3.2.1]octanols

1977 ◽  
Vol 55 (5) ◽  
pp. 841-848 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
Ring System ◽  
Hydroxyl Group ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr ◽  
Shielding Effects

The 13C nmr spectra of a series of 20 bicyclo[3.2.1]octanols and -octenols have been determined to examine the shielding effects of the hydroxyl group on the skeletal carbons in this ring system. For comparison, the previously unreported data for a few closely related alcohols in the [2.1.1], [2.2.1], and [3.2.2] systems were also collected. The utility of these substituent effects for configuraional and conformational assignments is discussed.

Reaction of Pyrylium Salts with Nucleophiles. Part 24.New Mono- and Bispyridinium Salts with a Central 2,5-Diaryloxazole Group

1997 ◽  
Vol 62 (5) ◽  
pp. 769-780 ◽  
Author(s):  
Iosif Schiketanz ◽  
Daniela Istrati ◽  
Calin Deleanu ◽  
Constantin Draghici ◽  
Alexandru T. Balaban
Keyword(s):  
Hydrazine Hydrate ◽  
Raney Nickel ◽  
Good Yield ◽  
Nmr Spectra ◽  
Amino Group ◽  
Aryl Ring ◽  
H Nmr ◽  
Pyrylium Salts ◽  
C Nmr

Reduction of nitro substituted 2,5-diaryloxazoles with hydrazine hydrate and Raney nickel affords in good yield 2,5-diaryloxazoles having amino group(s) on the aryl ring(s) . The reaction of 2,4,6-trisubstituted pyrylium perchlorates with mono- and diamino-2,5-diaryloxazoles yields new mono- and bispyridinium perchlorates with a central 2,5-diaryloxazole group. Their electronic, 13C NMR and 1H NMR spectra are presented and discussed.

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.

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