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.

Reaction of 3,4a-disubstituted 4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestane derivatives with reducing agents

1985 ◽  
Vol 50 (11) ◽  
pp. 2457-2470 ◽  
Author(s):  
Helena Velgová ◽  
Jaroslav Zajíček
Keyword(s):  
Sodium Borohydride ◽  
Reducing Agents ◽  
Epoxide Ring ◽  
Lithium Aluminium Hydride ◽  
H Nmr ◽  
Lithium Aluminium ◽  
Nmr Data ◽  
Epoxy Alcohols

Reaction of all stereoisomeric 3-acetoxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-ols I-IV with lithium aluminium hydride and reduction of 3-acetoxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-ones XXII and XXIII with sodium borohydride were studied. It was found that reductive opening of the 5β,6β-epoxide ring occured only in the case of the derivatives III and IV due to 5(O)n participation of the 3α-oxygen-containing substituent under formation of the transannular 3α,5α-epoxides VIII and IX, resp. On reduction of the 4a-keto epoxides XXII and XXIII with sodium borohydride the trans-epoxy alcohols III and I were formed. On the basis of 1H NMR data the conformation of the A-ring in the epoxides I-IV, XXII, and XXIII is also discussed.

Potential antidepressants: 2-(Phenylthio)aralkylamines

1989 ◽  
Vol 54 (7) ◽  
pp. 1995-2008 ◽  
Author(s):  
Jiří Jílek ◽  
Jiří Urban ◽  
Petr Taufmann ◽  
Jiří Holubek ◽  
Antonín Dlabač ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Benzyl Chloride ◽  
Lithium Aluminium Hydride ◽  
Pharmacological Profile ◽  
H Nmr ◽  
Lithium Aluminium ◽  
Alternative Approach ◽  
Phenyl Acetonitrile ◽  
Claisen Reaction ◽  
Pharmacological Testing

Reactions of 2-(phenylthio)benzyl chloride with dimethylamine, diethylamine, pyrrolidine, piperidine, morpholine, and 1-methylpiperazine afforded the title compounds VI-XI. Reaction of 2-(phenylthio)benzaldehyde with nitromethane gave the nitrostyrene XIV which was reduced with lithium aluminium hydride to 2-(2-(phenylthio)phenyl)ethylamine (XVI). This was transformed to the N-methyl and N,N-dimethyl derivatives XVIII and XIX. The Claisen reaction of (2-(phenylthio)phenyl)acetonitrile with ethyl acetate afforded compound XXI which was cleaved by phosphoric acid to (2-(phenylthio)phenyl)acetone (XX). The Leuckart-Wallach reaction afforded the formamide XXIII which was used as starting material for preparing the amines XXIV-XXVI. The alternative approach to these compounds starting by reaction of the aldehyde XII with nitroethane was complicated by the fact that in addition to the nitropropene XV 2-(phenylthio)benzonitrile was also formed. The synthetic use of the inhomogeneous XV resulted then in mixtures of amines XXIV-XXVI with IV-VI which was followed by means of mass and 1H NMR spectra. The amines XXIV-XXVI were oxidized to the sulfoxides XXVII-XXIX. The oily bases were transformed to crystalline salts and spectra of all homogeneous bases were recorded. Pharmacological testing showed the amine VI (VÚFB-15 370) to be a promising potential antidepressant. The amines XI and XXV showed also pharmacological profile of potential antidepressants.

Epimeric 17-hydroxy derivatives of 14β-androst-5-en-3β-yl acetate

1990 ◽  
Vol 55 (10) ◽  
pp. 2510-2520 ◽  
Author(s):  
Ivan Černý ◽  
Vladimír Pouzar ◽  
Miloš Buděšínský ◽  
Pavel Drašar ◽  
Miroslav Havel
Keyword(s):  
Sodium Nitrite ◽  
Sodium Borohydride ◽  
Nmr Spectra ◽  
H Nmr ◽  
Derivatives Of ◽  
Androstane Derivatives

A new, six-step synthesis of 3β-hydroxy-14β-androst-5-en-17-one (IX) starting from 3β-hydroxyandrost-5-en-17-one has been elaborated. Reduction of acetate X with sodium borohydride afforded 17α-hydroxy-14β-androst-5-en-3β-yl acetate (XI). The corresponding 17β-derivative XIV was obtained by epimerization of 17α-O-tosyl derivative XIII with sodium nitrite in hexamethylphosphoramide. The 13C and 1H NMR spectra of 14β-androstane derivatives are discussed.

Atropodiastereoisomerism and pseudoassymetry with axial chirality of ligands in bis(2-methyl-1-naphthyl)methanols

1979 ◽  
Vol 44 (10) ◽  
pp. 2946-2969 ◽  
Author(s):  
Otakar Červinka ◽  
Karel Bláha ◽  
Anna Fábryová ◽  
R. Fink ◽  
Dick Van der Helm ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Lithium Aluminium Hydride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Axial Chirality ◽  
H Nmr ◽  
Lithium Aluminium

On reduction of bis(2-methyl-1-naphthyl) ketone (I) with lithium aluminium hydride alcohol VI was formed which isomerized into alcohol VII. Both alcohols, the configuration of which were proved using 1H-NMR spectra and X-ray diffraction, represent the first example of compounds having a centrum of pseudoassymetry and axial chirality of ligands.

Flavan derivatives. XXIII. Preparation and synthetic applications of Flav-3-enes

1968 ◽  
Vol 21 (9) ◽  
pp. 2247 ◽  
Author(s):  
JW Clark-Lewis ◽  
RW Jemison
Keyword(s):  
Sodium Borohydride ◽  
Acidic Medium ◽  
Catalytic Reduction ◽  
Heterocyclic Ring ◽  
High Yield ◽  
Lithium Aluminium Hydride ◽  
Lower Field ◽  
Field Characteristic ◽  
Lithium Aluminium ◽  
New Synthesis

2'-Hydroxychalcones and α-alkoxy-2'-hydroxychalcones are converted by sodium borohydride in isopropanol into flav-3-enes and 3-alkoxyflav-3-enes in the convenient new synthesis which makes these flavenes readily available. Catalytic reduction of the flavenes gives the corresponding flavans or 3-alkoxyflavans in high yield, and the latter are obtained mainly in the 2,s-cis-form. The flavenes immediately give flavs lium cations in the cold when treated with acids in air, and oxidation of 5,7,3',4'-tetramethoxyflav-3-ene with benzoquinone in an acidic medium gave the flavylium salt, isolated as the ferrichloride. Reduction of 5,7,3',4'-tetramethoxy-flavylium chloride with lithium aluminium hydride gave 5,7,3',4'-tetramethoxy-flav-2-ene identical with the flavene obtained from (-)-epicatechin tetramethyl ether, and confirms an earlier investigation by Gramshaw, Johnson, and King. In its N.M.R. spectrum the heterocyclic-ring protons of this flav-2-ene give an ABX multiplet which is easily distinguished from the ABX multiplet at much lower field characteristic of flav-3-enes.

Photoreaktionen von Dekacarbonyldirhenium mit Allen und unverzweigten Allenderivaten / Photoreactions of Decacarbonyldirhenium with Allene and Unbranched Derivatives of Allene

1995 ◽  
Vol 50 (4) ◽  
pp. 649-660 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Wolfgang Michels ◽  
Gerhard Heeb
Keyword(s):  
Nmr Spectra ◽  
Crystal And Molecular Structure ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Oxidative Rearrangement ◽  
Dirhenium Complexes ◽  
Derivatives Of ◽  
By Products

Decacarbonyldirhenium (1) reacts upon UV irradiation with allene (2), 1,2-butadiene (3) and 2,3-pentadiene (4) preferentially by CO substitution and oxidative rearrangement to the corresponding enneacarbonyl-μ-η1:3-endiyl-dirhenium complexes 5, 9, and 15 and to the octacarbonyl-μ-η2:2-allene-dirhenium complexes 6, the stereoisomers 10, 11, and 16. At elevated temperature 5, 9, and 15 loose CO and yield by a reductive rearrangement also the complexes 6, 10, 11, and 16. In addition to these main products, depending upon the allene derivative used, various by-products are obtained.By-products of the reaction o f 1 with 2 are octacarbonyl-μ-η3:3-(2,3-dimethylene-buta-1,4- diyl)dirhenium (7) and μ-η2:2-allene-hexacarbonyl-μ-η1:3-1-propene-1,3-diyl-dirheniurn (8). The photo reaction of 1 with 3 yields, in addition to 9-11, tetracarbonyl-η3-(E-5-ethylidene- 4-methyl-2-cyclopenten-1-yl)rhenium (12) and tetracarbonyl-η3-(Z-5-ethyliden-4- methyl-2-cyclopenten-1-yl)rhenium (13) as a mixture of isomers. 1 and 4 form the by-products tetracarbonyl-η3-(EZ-3-penten-2-yl)rhenium (17), tetracarbonyl-η3-(EE-3-penten-2-yl)rhenium (18) and heptacarbonyl-μ-η1:2:1:2-(4,5-dimethyl-2,6-octadiene-3,6-diyl)dirhenium (19) with an unusually bridging and chelating ligand. The constitutions of the reaction products have been concluded from the IR and 1H NMR spectra. For 19 the crystal and molecular structure has been determined by X-ray diffraction analysis.

4,5-Seco-4,6-cyclosteroids. III. Observations on the course of reductive rearrangement of 6β-Bromo-4β,5-epoxy-5β-cholestan-3β-ol

1969 ◽  
Vol 22 (4) ◽  
pp. 807 ◽  
Author(s):  
DJ Collins ◽  
JJ Hobbs ◽  
RJ Rawson
Keyword(s):  
Hydrogen Bromide ◽  
High Yield ◽  
Lithium Aluminium Hydride ◽  
Experimental Conditions ◽  
Lithium Aluminium ◽  
Reaction Proceeds ◽  
Derivatives Of

It has been shown that reductive rearrangement of 6β-bromo-4β,5-epoxy- 5β-cholestan-3β-ol (I) to 4,5-seco-4,6-cycle-6β-cholestane-3β,5α-diol (IXa) with lithium aluminium hydride in tetrahydrofuran proceeds via 6β-bromo-5β-cholestane-3β,5-diol (IIa). Relevant reactions of the latter and the corresponding 3-ketone are discussed. ��� Similar conversion of the 3-epimer of (I) into 4,5-seco-4,6-cyclo- 6β-cholestane-3α,5α-diol (XIIIa) in high yield indicates that reductive rearrangement of the 6β-bromo-5β-hydroxy moiety proceeds without participation of the 3-aluminate complex. Some derivatives of (XIIIa) are described. ��� Experimental conditions required for the conversion of (I) into (IXa) are defined. ��� Combined evidence indicates that the reaction proceeds in a concerted manner by essentially base-catalysed, 1,3-elimination of hydrogen bromide from diol (IIa) with 4,5-bond migration to give the formal intermediate 3β-hydroxy-4,5-seco-4,6-cyclo-6β-cholestan-5-one (VI), further reduced to (IXa).

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 secondary alcohols of high optical purity

1986 ◽  
Vol 51 (2) ◽  
pp. 401-403 ◽  
Author(s):  
Otakar Červinka ◽  
Anna Fábryová ◽  
Irina Sablukova
Keyword(s):  
Nmr Spectroscopy ◽  
Optical Purity ◽  
Optically Active ◽  
Secondary Alcohols ◽  
Lithium Aluminium Hydride ◽  
Enantioselective Reduction ◽  
H Nmr ◽  
Lithium Aluminium ◽  
High Optical Purity ◽  
Optically Pure

Partially resolved enantiomers of optically active alcohols I-V, obtained by enantioselective reduction of the corresponding ketones with lithium aluminium hydride in the presence of (-)-quinine, were converted into crystalline 3,5-dinitrobenzoates or phenylcarbamates. The esters of the nearly optically pure enantiomers were separated by crystallization from the generally more soluble esters of the racemates. Optical purity of the hydrolytically liberated alcohols was determined by 1H NMR spectroscopy in the presence of chiral shifting agents.

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