Influence des groupes tert-butyle, triméthylsilyle et triméthylgermyle sur la stéréochimie de réactions d'addition en série cyclohexénique. II. Epoxydation des dérivés vinyliques et ouverture des époxydes par LiAlH4, MeOH/H+ et H2O/H+

1978 ◽  
Vol 56 (15) ◽  
pp. 2049-2052 ◽  
Author(s):  
Jean-Claude Richer ◽  
Marc-André Poirier ◽  
Yvette Maroni ◽  
Georges Manuel
Keyword(s):  
Ring Opening ◽  
Acidic Medium ◽  
Lithium Aluminium Hydride ◽  
Electronic Effects ◽  
Tert Butyl ◽  
Lithium Aluminium

Epoxidation of 1-tert-butyl (1a), 1-trimethylsilyl (1b), and 1-trimethylgermyl (1c) 4,4-dimethylcyclohexenes is described and the stereochemistry of the ring opening of the resulting epoxides (3a, 3b, 3c) by lithium aluminium hydride as well as methanol and water in acidic medium is examined. The regiochemistry of the ring opening of 3a is completely reversed, in the case of 3b and 3c, by the electronic effects of the trimethylsilyl and trimethylgermyl groups.

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.

Competing Radical- and Anion-Mediated Pathways in the Reduction of Bridgehead Tosylates with Lithium Aluminium Hydride

1999 ◽  
Vol 52 (5) ◽  
pp. 367 ◽  
Author(s):  
Ernest W. Della ◽  
Wit K. Janowski
Keyword(s):  
Electron Transfer ◽  
Ring Opening ◽  
Radical Anion ◽  
Lithium Aluminium Hydride ◽  
Trans Isomers ◽  
Lithium Aluminium ◽  
Mechanism Of Reaction ◽  
Anion Transfer

Reaction of norborn-1-yl tosylate with lithium aluminium hydride in boiling tetrahydrofuran affords a mixture of norbornan-1-ol accompanied by the ring-opened products 4-methylcyclohexanol and 3-ethylcyclopentanol as their cis/trans isomers, as well as p-thiocresol and p-tolyl disulfide. Evidence strongly suggests that the reaction is mediated by the norborn-1-yloxy radical rather than the norborn-1-yloxy anion. The process is initiated by very slow acyl oxygen fission of the norbornyl tosylate, followed by reduction of the derived p-toluenesulfinate ion to give the p-thiocresoxide anion. Transfer of an electron from the latter to the substrate and decomposition of the derived norborn-1-yl tosylate radical anion leads to the norborn-1-yloxy radical which, upon ring opening, generates the monocyclic alcohols via the corresponding ketones. It is noteworthy that, when norborn-1-yl mesylate is exposed to lithium aluminium hydride, it yields norbornan-1-ol exclusively. In the absence of an efficient electron-transfer agent, the mechanism of reaction of norborn-1-yl mesylate is suggested to involve acyl oxygen fission only.

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).

Influence des groupes tert-butyle, triméthylsilyle et triméthylgermyle sur la stéréochimie de réactions d'addition en série cyclohexénique. III. Epoxydation de cyclohexènes substitués en position allylique et réduction des époxydes par LiAlH4

1980 ◽  
Vol 58 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Jean-Claude Richer ◽  
Marc-André Poirier ◽  
Yvette Maroni ◽  
Georges Manuel
Keyword(s):  
Lithium Aluminium Hydride ◽  
Electronic Effects ◽  
Trimethylsilyl Group ◽  
Lithium Aluminium ◽  
Steric Factors ◽  
Cis And Trans

The epoxidation of allylic alkenes in the 6-tert-bulyl (or 6-trimethylsilyl or 6-trimethylgermyl) 3,3-dimethylcyclohexenes is examined; it has been found that the stereochemistry of these reactions is governed mostly by steric factors. The results obtained by the reduction of cis and trans epoxides by lithium aluminium hydride are also reported, the regiochemistry and the stereochemistry of the reactions of reduction are governed by steric factors as well as by the electronic effects of the trimethylsilyl group.

Convenient Synthesis of (Z)-7- and (E)-9-dodecene-1-yl Acetate, Components of Some Lepidoptera Insect Sex Pheromone

2017 ◽  
Vol 68 (1) ◽  
pp. 180-185
Author(s):  
Adriana Maria Andreica ◽  
Lucia Gansca ◽  
Irina Ciotlaus ◽  
Ioan Oprean
Keyword(s):  
Sex Pheromone ◽  
Coupling Reaction ◽  
Coupling Scheme ◽  
Lithium Aluminium Hydride ◽  
Terminal Alkyne ◽  
Mercury Derivative ◽  
Lithium Aluminium ◽  
Convenient Synthesis ◽  
Practical Synthesis ◽  
Insect Sex

Were developed new and practical synthesis of (Z)-7-dodecene-1-yl acetate and (E)-9-dodecene-1-yl acetate. The routes involve, as the key step, the use of the mercury derivative of the terminal-alkyne w-functionalised as intermediate. The synthesis of (Z)-7-dodecene-1-yl acetate was based on a C6+C2=C8 and C8+C4=C12 coupling scheme, starting from 1,6-hexane-diol. The first coupling reaction took place between 1-tert-butoxy-6-bromo-hexane and lithium acetylide-ethylendiamine complex obtaining 1-tert-butoxy-oct-7-yne, which is transformed in di[tert-butoxy-oct-7-yne]mercury. The mercury derivative was directly lithiated and then alkylated with 1-bromobutane obtaining 1-tert-butoxy-dodec-7-yne. After acetylation and reduction with lithium aluminium hydride of 7-dodecyne-1-yl acetate gave (Z)-7-dodecene-1-yl acetate with 96 % purity. The synthesis of (E)-9-dodecene-1-yl acetate was based on a C8+C2=C10 and C10+C2=C12 coupling scheme, starting from 1,8-octane-diol. The first coupling reaction took place between 1-tert-butoxy-8-bromo-octane and lithium acetylide-ethylendiamine complex obtaining 1-tert-butoxy-dec-9-yne, which is transformed in di[tert-butoxy-dec-9-yne]mercury. The mercury derivative was directly lithiated and then alkylated with 1-bromoethane obtaining 1-tert-butoxy-dodec-9-yne. After reduction with lithium aluminium hydride of 1-tert-butoxy-(E)-9-dodecene and acetylation was obtained (E)-9-dodecene-1-yl acetate with 97 % purity.

3-(s-Hydrindacen-4-yl)propylamines and 4-(s-hydrindacen-4-yl)butylamines; Synthesis and pharmacological screening

1981 ◽  
Vol 46 (8) ◽  
pp. 1800-1807 ◽  
Author(s):  
Zdeněk Vejdělek ◽  
Marie Bartošová ◽  
Miroslav Protiva
Keyword(s):  
Malonic Acid ◽  
Local Anaesthetics ◽  
Lithium Aluminium Hydride ◽  
Spasmolytic Activity ◽  
Lithium Aluminium ◽  
Malonic Acid Derivatives ◽  
Pharmacological Screening ◽  
Hydroxyethyl Piperazine

4-Chloromethyl-s-hydrindacene (VIIa) was transformed via the malonic acid derivatives VIIIa and IXa to the acid Xb which afforded in four steps the homological acid Xc. Reactions of chlorides of both acids (XIbc ) with dimethylamine, 1-methylpiperazine and 1-(2-hydroxyethyl)piperazine led to the amides XIIbc-XIVbc which were reduced with lithium aluminium hydride to the title compounds IVcd-VIcd. The amines obtained show central neuroleptic effects only in subtoxic doses; they are also potent local anaesthetics and have significant spasmolytic activity of the neurotropic as well as musculotropic type.

Substituted N,N-Dimethyl-3-(phenylthio)- and -4-(phenylthio)benzylamines

1992 ◽  
Vol 57 (1) ◽  
pp. 194-203 ◽  
Author(s):  
Karel Šindelář ◽  
Vojtěch Kmoníček ◽  
Marta Hrubantová ◽  
Zdeněk Polívka
Keyword(s):  
Serotonin Receptors ◽  
Hydrobromic Acid ◽  
Antidepressant Activity ◽  
Benzoic Acids ◽  
Lithium Aluminium Hydride ◽  
Acid Chlorides ◽  
Activity Inhibition ◽  
Lithium Aluminium ◽  
The Brain

(Arylthio)benzoic acids IIa - IIe and VIb - VId were transformed via the acid chlorides to the N,N-dimethylamides which were reduced either with diborane "in situ" or with lithium aluminium hydride to N,N-dimethyl-(arylthio)benzylamines Ia - Ie and Vb - Vd. Leuckart reaction of the aldehydes IX and X with dimethylformamide and formic acid afforded directly the amines Va and Ve. Demethylation of the methoxy compounds Ia and Ve with hydrobromic acid resulted in the phenolic amines If and Vf. The most interesting N,N-dimethyl-4-(phenylthio)benzylamine (Va) hydrochloride showed affinity to cholinergic and 5-HT2 serotonin receptors in the rat brain and some properties considered indicative of antidepressant activity (inhibition of serotonin re-uptake in the brain and potentiation of yohimbine toxicity in mice).

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