Preparation and Conformational Study of B-Ring Substituted Lupane Derivatives

2006 ◽  
Vol 71 (8) ◽  
pp. 1131-1160 ◽  
Author(s):  
Martin Dračínský ◽  
Simona Hybelbauerová ◽  
Jan Sejbal ◽  
Miloš Buděšínský
Keyword(s):  
Double Bond ◽  
Hydroxy Group ◽  
Molecular Modelling ◽  
Nmr Spectra ◽  
Hydroxy Derivative ◽  
Secondary Hydroxy Group ◽  
Conformational Study ◽  
Primary Hydroxy Group ◽  
Type 3 ◽  
C Nmr

New lupane-type triterpenoids with 5(6) double bond were prepared using the method of partial demethylation on carbon C-4. Hydroboration of the double bond led to 6α-hydroxy derivative. By the oxidation and following reduction of 6α-hydroxy derivative the 6-oxo and 6β-hydroxy derivatives were prepared. A new method for selective oxidation of secondary hydroxy group in the presence of primary hydroxy group was performed. The conformation of ring A of new lupane-type 3-oxo derivatives with a substituent on ring B was elucidated on the bases of 1H and 13C NMR spectra and molecular modelling.

Preparation of New Oxidized 18-α-Oleanane Derivatives

2005 ◽  
Vol 70 (9) ◽  
pp. 1447-1464 ◽  
Author(s):  
Miroslav Kvasnica ◽  
Iva Tišlerová ◽  
Jan Šarek ◽  
Jan Sejbal ◽  
Ivana Císařová
Keyword(s):  
Double Bond ◽  
Nmr Spectra ◽  
Biological Activities ◽  
Oxidative Cleavage ◽  
Allylic Oxidation ◽  
Unsaturated Ketone ◽  
Ruthenium Tetroxide ◽  
Unsaturated Compounds ◽  
Starting Compound ◽  
C Nmr

19β,28-Epoxy-4,5-seco-3,5-cyclo-18α-olean-3(5)-ene (2) is an appropriate compound for oxidations, which lead to new oxidized compounds with potential biological activities. Several oxidations were used such as epoxidation, allylic oxidation, oxidative cleavage of double bond and other ones. From the starting compound epoxides 3a, 3b and unsaturated ketone 4 were prepared. This ketone was further oxidized to diketone 6 and anhydride 7. The double bonds of all unsaturated compounds were cleaved with ruthenium tetroxide to afford new A-seco oleananes. The structure and stereochemistry of the compounds were derived from IR, MS, 1H and 13C NMR spectra (1D and 2D COSY, TOCSY, NOESY, HSQC, HMBC).

Assignment of Nitrogen Stereochemistry of Agroclavine and Elymoclavine 6-N-Oxides

1995 ◽  
Vol 60 (12) ◽  
pp. 2165-2169 ◽  
Author(s):  
Vladimír Křen ◽  
Jan Němeček ◽  
Věra Přikrylová
Keyword(s):  
Hydrogen Peroxide ◽  
Absolute Configuration ◽  
Molecular Modelling ◽  
Nmr Spectra ◽  
Peroxide Oxidation ◽  
Hydrogen Peroxide Oxidation ◽  
C Nmr

Both possible 6-N-oxides of agroclavine (I) and elymoclavine (II) were prepared by hydrogen peroxide oxidation. Their 1H and 13C NMR spectra were assigned and the conformation of the D ring (half-chair) was determined. Absolute configuration at 6-N was established by NMR and molecular modelling.

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 and Conformational Study of 19β,28-Epoxy-18α-olean-5-ene Derivatives

2006 ◽  
Vol 71 (3) ◽  
pp. 387-410 ◽  
Author(s):  
Martin Dračínský ◽  
Václav Richtr ◽  
Václav Křeček ◽  
Jan Sejbal ◽  
Jiří Klinot ◽  
...  
Keyword(s):  
Double Bond ◽  
Coupling Constants ◽  
Conformational Study ◽  
Hydrogen Atoms ◽  
Vicinal Coupling Constants ◽  
Starting Compound ◽  
New Type ◽  
Type 3

New oleanane type triterpenoids with the 5(6) double bond were prepared using partial demethylation on carbon C-4. The starting compound was 23-hydroxybetulin (1b) and the key reaction was the methylation of 19β,28-epoxy-24-nor-18α-olean-4-en-3-one (3b). The 5(6) double bond was used in preparation of new derivatives with an epoxy or oxo substituent in ring B. The conformation of ring A of new type 3-oxo oleanane derivatives with a double bond or a substituent on ring B was elucidated from vicinal coupling constants of hydrogen atoms in positions 1 and 2.

Preparation of 12,20-disubstituted lupane derivatives

1979 ◽  
Vol 44 (1) ◽  
pp. 194-210 ◽  
Author(s):  
Vladimír Pouzar ◽  
Alois Vystrčil
Keyword(s):  
Hydroxy Group ◽  
Sodium Borohydride ◽  
Nmr Spectra ◽  
Unsaturated Ketone ◽  
Lithium Aluminium Hydride ◽  
H Nmr ◽  
Unsaturated Alcohols ◽  
Lithium Aluminium ◽  
Primary Hydroxy Group ◽  
Derivatives Of

Ketoester I was reduced to diol VI. The higher reactivity of its primary hydroxy group was made use of for the preparation of 12α-hydroxy derivatives VII, VIII and X the oxidation of which led to oxo derivatives XII, XIII and XIV. The reduction of the 12-oxo group in compounds XII and XIV with lithium aluminium hydride takes place stereospecifically under formation of 12α-hydroxy derivatives VII and X, while on reduction with sodium in 1-propanol corresponding 12β-hydroxy derivatives XV and XVI are also formed. Reduction of the unsaturated ketone XVII with sodium borohydride gave unsaturated alcohols XVIII and XX. As acetoxy ketone XXIV was obtained from olefin XIX in a 12% yield only, its alternative preparation was carried out from acetoxy ketone XXXIV via the intermediates XXXII, XXXV, XXVIII and XXXI in an overall yield of 27%. The structures of the derivatives of 12-lupene (III, V, XVII, XIX and XXI), 12-lupanol (II, VII, X, XV, XXXI and XXVII) and 12-lupanone (I, XII, XIII, XIV, XXIII, XXIV, XXXIII and XXXIV) were confirmed by the analysis of their 1H NMR spectra.

NMR and conformational study of branched oligosaccharides containing 2,3-disubstituted residues of α-L-rhamnose

1990 ◽  
Vol 68 (7) ◽  
pp. 1238-1250 ◽  
Author(s):  
Grigory M. Lipkind ◽  
Nikolay E. Nifant'ev ◽  
Alexander S. Shashkov ◽  
Nikolay K. Kochetkov
Keyword(s):  
Experimental Data ◽  
Conformational Analysis ◽  
Nmr Spectra ◽  
Conformational Study ◽  
Theoretical Conformational Analysis ◽  
Conformational States ◽  
Nuclear Overhauser ◽  
C Nmr

1H and 13C NMR spectra have been recorded and the nuclear Overhauser enhancements (in D2O), after pre-irradiation of the anomeric protons, have been measured for tri- and tetrasaccharides containing 2,3-disubstituted residues of α-L-rhamnose and the corresponding disaccharides. The proximity of the conformational states of the disaccharide units in these branched oligosaccharides and in the corresponding disaccharides has been shown, on the basis of both the nOe experimental data and theoretical conformational analysis. This conclusion is also confirmed by data for glycosylation effects in the 13C NMR spectra of the oligosaccharides. Keywords: branched oligosaccharides, 1H and 13C NMR spectra, conformations.

New investigations of the reaction of epichlorohydrin with hindered amines: X-ray and NMR analyses

1989 ◽  
Vol 67 (10) ◽  
pp. 1514-1522 ◽  
Author(s):  
Michel Laguerre ◽  
Chantal Boyer ◽  
Jean-Michel Leger ◽  
Alain Carpy
Keyword(s):  
Hydroxy Group ◽  
Amino Alcohol ◽  
Structure Elucidation ◽  
Nmr Spectra ◽  
Secondary Amines ◽  
Primary Amines ◽  
Nmr Studies ◽  
X Ray ◽  
Hindered Amines ◽  
C Nmr

During the synthesis of a series of new antiarhythmic drugs, the reaction between epichlorohydrin and hindered amines was reinvestigated. With primary amines, 3-azetidinols were formed in fair yields. The X-ray structure elucidation of one of these compounds (1: P21/n, a = 17.210, b = 6.665, c = 23.585, β = 102.29, and R = 0.064 for 2005 observed reflections) and NMR studies led to the conclusion that both the hydroxy group and the bulky nitrogen substituent are on the same side of the azetidine ring. With secondary amines, the reaction was very complex, leading to diamino dioxane, diamino alcohols, amino alcohol ethers, and one glycol. X-ray analysis and 1H and 13C NMR studies allowed complete assignments for all compounds. All but one exhibited a slow interconversion of the nitrogen visible in the 13C NMR spectra. Keywords: epichlorohydrin, hindered amines, azetidinol, adamantane, alkanol amines.

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