The Stereochemistry of Raney Nickel Action. III. The Stereochemical Course of Dehydroxylations in the Benzyl Alcohol Series

Bonner, William A.; Zderic, John A.; Casaletto, George A.

doi:10.1021/ja01140a027

Cited by 29 publications

(12 citation statements)

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“…It is now proved unequivocally that the catalytic replacement of OH by H takes place with retention also in our case, as had been claimed for this reaction in general [4]. 2.…”

Section: Nme2supporting

confidence: 88%

“…CI Recently, we [3] described the chemical correlation between compounds 1 4 , including the catalytic replacement of an OH group by H. Although it is claimed [4] that this step can take place with retention, we nevertheless had to prove this independently for our compounds. For the sake of clarity, the same absolute configuration at the chiral centre has been assumed throughout, although in some cases actually the enantiomer had been investigated.…”

Section: Nme2mentioning

confidence: 99%

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Circular Dichroism of Some 2‐(Phenylmethyl)pyridine Derivatives

Berova

Eojadziev

Bresciani–Pahor

et al. 1990

Helvetica Chimica Acta

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The absolute configuration of the 2-(phenylmethy1)pyridine derivatives 1-9 had been established by X-ray diffraction and chemical correlation. Their CD spectra have been studied in different solvents for the free and protonated forms. It has now been found that, from the sign of the strong CD couplet between 270 and 220 nm, which was observable for all these compounds besides 7 and 9, their absolute configuration can be determined much quicker.

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“…It is now proved unequivocally that the catalytic replacement of OH by H takes place with retention also in our case, as had been claimed for this reaction in general [4]. 2.…”

Section: Nme2supporting

confidence: 88%

Section: Nme2mentioning

confidence: 99%

Circular Dichroism of Some 2‐(Phenylmethyl)pyridine Derivatives

Berova

Eojadziev

Bresciani–Pahor

et al. 1990

Helvetica Chimica Acta

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“…Die Arbeitsgruppen von Bortner und Mitsui haben ihre Stereochemie untersucht und festgestellt, dass optisch aktive benzylartige Gruppen, die an Sauerstoff gebunden sind, an Nickel-Katalysatoren unter Retention der Konfiguration abgespalten werden [2] [9]. Fur 2-Anilino-2-phenyl-propionsaure und ihren Methylester wurde an Pd-Katalysatoren iiberwiegend Retention vermutet [9], was im Gegensatz zu der Hydrogenolyse von 0-Benzylverbindungen steht.…”

Section: S( +)-2-dimethylamino-2-phenyl-propionic Acid (I) and Its Deunclassified

Über die Stereochemie der Hydrogenolyse von N‐Benzyl‐Bindungen I. Die Hydrogenolyse von Derivaten der 2‐Amino‐2‐phenyl‐propionsäure.

Dahn

Garbarino

O'murchu

1970

Helvetica Chimica Acta

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Herrn Dr. 0 . Isler zum 60. Geburtstag gewidmet (26. VI. 70)Summary. The stereochemistry of the hydrogenolysis of benzyl-N bonds was studied using S( +)-2-dimethylamino-2-phenyl-propionic acid (I) and its derivatives, and R( -)-2-anilino-2phenyl-propionic acid (11). The configuration of I was confirmed, that of I1 established by ORD. measurements, after transformation of the phenyl into cyclohexyl groups. On a palladium catalyst the hydrogenolysis of I, its methyl and ethyl esters and its amide proceeded with 72 to 99% inversion of configuration, that of I1 with at least 66% inversion. The ester of the quaternary ammonium derivative of I gave as much inversion as retention (= racemisation). Die katalytische Hydrogenolyse von Benzylderivaten, eine Reaktion von praparativer Bedeutung, ist in bezug auf ihren Mechanismus noch nicht genau bekannt. Die Arbeitsgruppen von Bortner und Mitsui haben ihre Stereochemie untersucht und festgestellt, dass optisch aktive benzylartige Gruppen, die an Sauerstoff gebunden sind, an Nickel-Katalysatoren unter Retention der Konfiguration abgespalten werden [2] [3] [4], an Palladium dagegen unter uberwiegender Inversion [4] [5]. Die Grunde fur diesen Unterschied sind nicht genau bekannt; es kann sich um unterschiedliche Adsorption handeln [4] [5] [6]. Leichter spaltbare Verbindungen wie substituierte Benzylhalogenide [7] liefern racemisierte Hydrogenolysenprodukte ; dies gilt auch fur S-Benzylverbindungen [S], vielleicht infolge von Katalysatorvergiftung. I n diesem Zusammenhang ware es interessant, das stereochemische Verhalten von N-Benzylverbindungen zu kennen. Bonner & Zderic [3] sowie Mitsui & Sato [9] erzielten mit 2-Amino-2-phenyl-propionsaure-athylester [ 101 nur bei hoher Temperatur eine Hydrogenolyse der C-N-Bindung, neben Hydrierung des Benzolringes ; mit Pd wurde uberwiegend Racemisierung beobachtet [9]. Fur 2-Anilino-2-phenyl-propionsaure und ihren Methylester wurde an Pd-Katalysatoren iiberwiegend Retention vermutet [9], was im Gegensatz zu der Hydrogenolyse von 0-Benzylverbindungen steht. l) Aus den Dissertationen J . A.Garbarino, Lausanne 1966, und C. O'Murchu, Lausanne 1967. Vorlaufige Mitteilung s. [l].

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“…12 A detailed description of resolution techniques in terms of thermodynamics is given by Jacques et al 13 If the compound of interest is either a carboxylic acid or an organic base, resolution can be achieved by diastereomeric salt formation. [13][14][15][16] In many cases a racemate of a chiral carboxylic acid has been resolved using a naturally occurring chiral amine. 17 However, resolution is usually not complete after a single crystallization, and the partially resolved material has to be recrystallized.…”

Section: Introductionmentioning

confidence: 99%

Resolution of ephedrine in supercritical CO2: A novel technique for the separation of chiral drugs

Kordikowski

York

Latham

1999

Journal of Pharmaceutical Sciences

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Racemic ephedrine has been resolved by diastereomeric salt formation with mandelic acid using supercritical CO(2) as precipitating agent. Crystallizations were performed using the Solution Enhanced Dispersion by Supercritical Fluids (SEDS) technique. Temperature was varied between 35 and 75 degrees C, and pressures ranged from 100 to 350 bar. Resolution, determined by chiral capillary electrophoresis, is described as a function of temperature and density of the supercritical fluid. A comparison of SEDS-produced material with a conventional resolution method shows that SEDS-crystallized material exhibits identical properties to conventionally crystallized material.

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The Stereochemistry of Raney Nickel Action. III. The Stereochemical Course of Dehydroxylations in the Benzyl Alcohol Series

Cited by 29 publications

References 0 publications

Circular Dichroism of Some 2‐(Phenylmethyl)pyridine Derivatives

Circular Dichroism of Some 2‐(Phenylmethyl)pyridine Derivatives

Über die Stereochemie der Hydrogenolyse von N‐Benzyl‐Bindungen I. Die Hydrogenolyse von Derivaten der 2‐Amino‐2‐phenyl‐propionsäure.

Resolution of ephedrine in supercritical CO2: A novel technique for the separation of chiral drugs

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