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.

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.

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.

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.

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.

Synthesis and stereochemistry of 1-Thiaflavan-4-ols

1966 ◽  
Vol 19 (7) ◽  
pp. 1251 ◽  
Author(s):  
GF Katekar
Keyword(s):  
Sodium Borohydride ◽  
Nitrous Acid ◽  
Lithium Aluminium Hydride ◽  
Lithium Aluminium

Lithium aluminium hydride or sodium borohydride reduced 1-thiaflavanone, 6-methyl-1-thiaflavanone, and 4'-chloro-1-thiaflavanone to the corresponding 2,4-cis-1-thiaflavan-4-ols. Deamination of 2,4-cis-4-amino-1-thiaflavans with nitrous acid gave rise to the 2,4-trans-1-thiaflavan-4-ols. N.m.r. measurements were used to determine the stereochemistry of these compounds.

Reaction of lithium aluminium hydride with 4,4-dimethyl-4a,5-epoxy-A-homocholestane derivatives and mass spectral fragmentation of some degradation products

1982 ◽  
Vol 47 (7) ◽  
pp. 2007-2023
Author(s):  
Helena Velgová ◽  
Antonín Trka
Keyword(s):  
Main Product ◽  
Degradation Products ◽  
Molecular Ions ◽  
Point Of View ◽  
Epoxide Ring ◽  
Lithium Aluminium Hydride ◽  
Electronic Effects ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Lithium Aluminium

Reductive opening of the epoxide ring of stereoisomeric 4,4-dimethyl-4a,5-epoxy-A-homocholestane derivatives with oxygen containing substituent (OH, OCOCH3, OCH3) in the position 3 was investigated. In the absence of other directing effects, than the stereoelectronic ones, the epoxide ring of 4aα,5α-epoxides is opened at the side of the less substituted carbon C(4a), under formation of 5α-hydroxy derivatives, while in the case of 4aβ,5β-epoxides both the cleavage of the C(4a)-O bond, leading to the formation of 5β-hydroxy derivatives, and the cleavage of the C(5)-O bond, leading to the formation of 4aβ-hydroxy-5,6-unsaturated derivatives take place. The participation of the substituent in the position 3 leads to an abnormal cleavage both in 4aα,5α-and 4aβ,5β-epoxides, i.e. to the cleavage of the C(5)-O bond under formation of 3,5-epoxides. The effect of the character of the substituent in the position 3 on the direction of the reductive cleavage of the epoxide ring is also discussed from the point of view of conformational and electronic effects. In mass spectrometry the main product of the fragmentation of the molecular ions of the 4a-hydroxy-3,5-epoxides XIII and XXV and the 4a-ketones XVII and XXVIII is the ion [C23H40O]+. which is formed after the breaking of the C(3)-O bond by the splitting off of the ring A. The fragmentation of the molecular ion of the semi-ketal XVIII is determined by the cleavage of the epoxide bond O-C(5).

Utilization of 1,6-anhydrohexoses for the preparation of some aliphatic adenosine analogs

1989 ◽  
Vol 54 (10) ◽  
pp. 2753-2766 ◽  
Author(s):  
Marcela Krečmerová ◽  
Miloslav Černý ◽  
Miloš Buděšínský ◽  
Antonín Holý
Keyword(s):  
Hydrochloric Acid ◽  
Sodium Borohydride ◽  
Sodium Salt ◽  
Dilute Hydrochloric Acid ◽  
Lithium Aluminium Hydride ◽  
Subsequent Reduction ◽  
Adenosine Analogs ◽  
Lithium Aluminium

Reaction of sodium salt of adenine with 1,6:3,4-dianhydro-2-O-p-toluenesulfonyl-β-D-galactopyranose (I) afforded 4-(adenin-9-yl)-1,6:2,3-dianhydro-4-deoxy-β-D-mannopyranose (II) and 2,4-bis(adenin-9-yl)-1,6-anhydro-2,4-dideoxy-β-D-glucopyranose (IV). Compound II was converted into 4-(adenin-9-yl)-1,6-anhydro-4-deoxy-β-D-glucopyranose (VI). Cleavage of the 1,6-anhydro bond in this compound with hot concentrated hydrochloric acid led to 4-(adenin-9-yl)-4-deoxy-D-glucose (VIII) which was reduced with sodium borohydride to give 4-(adenin-9-yl)-4-deoxy-D-glucitol (IX). Epoxide II was reduced with lithium aluminium hydride and the obtained 4-(adenin-9-yl)-1,6-anhydro-2,4-dideoxy-β-D-arabinohexopyranose (VII) on treatment with dilute hydrochloric acid and subsequent reduction with sodium borohydride gave 4-(adenin-9-yl)-2,4-dideoxy-D-arabino-hexitol (XI).

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