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.

New synthesis of 2-amino-4-oxopyrido[3,2-e]-1,3-thiazines and 1-alkyl(aryl)pyrido[3,2-e]-2-thiouracils

1983 ◽  
Vol 48 (11) ◽  
pp. 3315-3328 ◽  
Author(s):  
Dušan Koščík ◽  
Pavol Kristian ◽  
Jozef Gonda ◽  
Emília Dandárová
Keyword(s):  
Mass Spectra ◽  
Nmr Spectra ◽  
Secondary Amines ◽  
Primary Amines ◽  
Addition Reactions ◽  
Alkyl Aryl ◽  
H Nmr ◽  
New Synthesis ◽  
Subsequent Cyclization ◽  
C Nmr

Addition reactions of 2-chloronicotinoyl isothiocyanate with primary and secondary amines and subsequent cyclization of intermediate thioureas represent new synthesis of pyrido[3,2-e]thiouracil and pyrido[3,2-e]-thiazine derivatives. 2-Amino-4-oxopyrido[3,2-e]-1,3-thiazines are formed upon heating the reaction components in ethanol, whereas 1-alkyl(aryl)pyrido[3,2-e]-2-thiouracils are products of alkali-catalyzed reaction. In reaction with primary amines the corresponding thioureas were isolated as intermediates, whereas secondary amines reacted directly to give the pyridothiazine derivatives. Structure of the synthesized compounds was confirmed by their 13C NMR and mass spectra; also the IR and 1H NMR spectra are in accord with the suggested formulae.

Functionalization of 3β,28-lupanediol diacetate with chromium(VI) oxide

1991 ◽  
Vol 56 (12) ◽  
pp. 2936-2949 ◽  
Author(s):  
Jan Sejbal ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jiří Protiva
Keyword(s):  
Double Bond ◽  
Functional Groups ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Functional Group ◽  
Oxygen Functional Group ◽  
Chromium Vi ◽  
C Nmr

The oxidation of 3β,28-lupanediol diacetate (I) with chromium(VI) oxide gives low yields of products with functional groups in the ring E as products of hydroxylation at the 19β position (IV, VI, and IX) and the 11-ketone VII which has been transformed into other lupane derivatives with an oxygen functional group at 11 position (VIII, XIII - XV) or with a 9(11)-double bond (XVI, XVII). Structure of the compounds prepared has been verified by their 1H and 13C NMR spectra as well as by their mass spectra.

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).

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.

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.

Formen des Diphenylgermaniumoxids(Ph2GeO)x, x = 3, 4, n / Phases of Diphenylgermanium Oxide(Ph2GeO)x, x = 3, 4, n

1984 ◽  
Vol 39 (7) ◽  
pp. 868-875 ◽  
Author(s):  
Ludwig Roß ◽  
Martin Dräger
Keyword(s):  
Crystal Structure ◽  
Thermal Analysis ◽  
Vibrational Spectra ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Membered Ring ◽  
Tetragonal Crystals ◽  
Hydroxy Groups ◽  
C Nmr

Diphenylgermanium oxide can be obtained trimeric (6 -membered ring, monoclinic crystals), tetrameric (8 -membered ring, monoclinic and tetragonal crystals and monoclinic with half a mole of crystal ethanol) and polymeric with terminating hydroxy groups. Transitions are investigated by thermal analysis, mass spectra and 13C NMR spectra. The vibrational spectra (I. R . and Raman) of the forms are discussed . The crystal structure of the monoclinic (Ph :GeO)4 has been determined and refined to R = 0.051. The symmetry of the molecule is near to S4 (distances Ge - O 174.7 - 176.2, Ge - C 190.0 - 194.6 pm, angles Ge - O - Ge 131.2 - 136.9, O - Ge - O 107.8 -110.3 °).

The structure of demethoxyrapamycin

1982 ◽  
Vol 60 (15) ◽  
pp. 2046-2047 ◽  
Author(s):  
John A. Findlay ◽  
Jia-Sen Liu ◽  
D. Jean Burnell ◽  
Thomas T. Nakashima
Keyword(s):  
High Field ◽  
Mass Spectra ◽  
Nmr Spectra ◽  
Antifungal Antibiotic ◽  
C Nmr

The structure 2, 29-demethoxyrapamycin, is proposed for a new antibiotic from Streptomyceshygroscopicus and has been deduced by comparison of high field 1H and 13C nmr spectra, ir, uv, and mass spectra, and ORD/CD curves with those of the known antifungal antibiotic rapamycin 1.

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.

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.

Reactions of steroidal 5,6-epoxides and cyclohexene oxide with aluminum alkoxides

1985 ◽  
Vol 63 (10) ◽  
pp. 2763-2768 ◽  
Author(s):  
Herbert L. Holland ◽  
Saeed R. Khan
Keyword(s):  
Lewis Acid ◽  
Nmr Spectra ◽  
Addition Reactions ◽  
Aluminum Isopropoxide ◽  
Carbonyl Groups ◽  
Cyclohexene Oxide ◽  
Epoxide Opening ◽  
C Nmr

The isomeric 5,6α- and 5,6β-epoxycholestanes, in addition to an analogous series of compounds substituted at C-3 with hydroxy (α or β stereochemistry) or ethylene ketal groups, have been treated with aluminum isopropoxide or tert-butoxide. The latter series of reactions did not give identifiable material, but aluminum isopropoxide gave products derived from epoxide opening and rearrangement in all cases. With epoxides unsubstituted at C-3, aluminum isopropoxide functioned as a Lewis acid in promoting epoxide rearrangements. In the presence of a C-3 alcohol function, additional products were obtained arising from fragmentation of the C-4,C-5 bond, or from β-elimination of the epoxide involving the loss of a C-7 hydrogen. Meerwein–Pondorff reduction of product carbonyl groups was also observed. C-3 ketal substituted epoxides were rearranged cleanly to 6-hydroxy-Δ4-3-ketones. Cyclohexene oxide reacted with aluminum isopropoxide (but not with tert-butoxide) to give two products arising from epoxide addition reactions. Structures for these products are proposed based on their 13C nmr spectra, and a possible route for their formation is presented. None of the epoxides examined in this study reacted with magnesium methoxide.

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