Über die katalytische Reduktion von Mandelsäuren

Rosenmund, Karl W.; Schindler, H.

doi:10.1002/ardp.192800083

Cited by 9 publications

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“…A crucial factor influencing selectivity in the catalytic hydrogenation of nitriles is the nature of the catalyst [48][49][50][51][52][53][54][55][56]. In order to hydrogenate the nitrile in compound (S)-3 with the highest yield towards (S)-tembamide, minimizing the hydrogenolysis of the C-O bond from the benzyloxy group and the formation of secondary and tertiary amines, a transition metal catalyst screening was performed.…”

Section: Catalyst Screeningmentioning

confidence: 99%

“…Besides the intrinsic side reactions associated with the catalytic reduction shown above, selectivity is very important, since the reactions at other functional groups in the molecule would result in undesired side products. For example, the C−O bond of the benzyloxy group is especially susceptible to hydrogenolysis, due to the phenyl ring of the cyanohydrin fragment (see Scheme 3) [37,51,52]. The chemoselectivity of the catalytic hydrogenation of nitriles depends on the substrate structure, the nature and loading of catalyst, the reaction temperature, the hydrogen pressure, the selected solvent and the presence of basic additives such as ammonia [46−48].…”

Section: Introductionmentioning

confidence: 99%

“…Besides the intrinsic side reactions associated with the catalytic reduction shown above, selectivity is very important, since the reactions at other functional groups in the molecule would result in undesired side products. For example, the C-O bond of the benzyloxy group is especially susceptible to hydrogenolysis, due to the phenyl ring of the cyanohydrin fragment (see Scheme 3) [37,51,52]. condensation reactions that take place between the reduction intermediate imines (II) with the formed amines (III and VI) as shown in Scheme 2 [46][47][48].…”

Section: Introductionmentioning

confidence: 99%

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Multi-Catalytic Route for the Synthesis of (S)-Tembamide

et al. 2019

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Enantiopure β-amino alcohols constitute one of the most significant building blocks for the synthesis of active pharmaceutical ingredients. Despite the availability of a range of chiral β-amino alcohols from a chiral pool, there is a growing demand for new enantioselective synthetic routes to vicinal amino alcohols and their derivatives. In the present study, an asymmetric 2-step catalytic route that converts 4-anisaldehyde into a β-amino alcohol derivative, (S)-tembamide, with excellent enantiopurity (98% enantiomeric excess) has been developed. The recently published initial step consists in a concurrent biocatalytic cascade for the synthesis of (S)-4-methoxymandelonitrile benzoate. The O-benzoyl cyanohydrin is then converted to (S)-tembamide in a hydrogenation reaction catalyzed by Raney Ni. To achieve hydrogenation of the nitrile moiety with highest chemoselectivity and enantioretention, various parameters such as nature of the catalyst, reaction temperature and hydrogen pressure were studied. The reported strategy might be transferrable to the synthesis of other N-acyl-β-amino alcohols.

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Section: Catalyst Screeningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Besides the intrinsic side reactions associated with the catalytic reduction shown above, selectivity is very important, since the reactions at other functional groups in the molecule would result in undesired side products. For example, the C-O bond of the benzyloxy group is especially susceptible to hydrogenolysis, due to the phenyl ring of the cyanohydrin fragment (see Scheme 3) [37,51,52]. condensation reactions that take place between the reduction intermediate imines (II) with the formed amines (III and VI) as shown in Scheme 2 [46][47][48].…”

Section: Introductionmentioning

confidence: 99%

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Multi-Catalytic Route for the Synthesis of (S)-Tembamide

et al. 2019

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Hydrogenolysis of Benzyl Groups Attached to Oxygen, Nitrogen, or Sulfur

Hartung¹,

Simonoff²

2011

Organic Reactions

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The benzyl group and a variety of substituted benzyl groups attached to an oxygen atom as in alcohols, ethers, acetals, or esters; to an amino nitrogen atom; or to a sulfur atom in thio ethers may be removed as toluene, or the corresponding substituted toluene, by hydrogenolysis. Other chemical and catalytic methods have been employed to bring about these debenzylations. It is the purpose of this chapter to give illustrations of both types of debenzylations so that their usefulness may be appreciated.

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Die Umwandlung von Arylcarbinolen in Desoxyverbindungen durch katalytische Reduktion ihrer Ester

Zymalkowski

1954

Archiv der Pharmazie

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Bd. 207.159 1954, NI. 9/10 Die Urnwandlung ron Arylcarbinolen in Deloxyverbindungen mille. Auch der gelbe Fleck mit dem RE'-Wert 0,85 ist bei der Schafgarbe sichtbar. Dagegen mussen die beiden unteren Flecke von Rzulenvorstufen entstanden sein, die in der Kamille nicht vorhanden sind. Die drei Flecke sind bei verschiedenen Schafgarben verschieden stark ausgebildet. Achillea Millefolium scheint nach den papierchromatischen Ergebnissen ein Gemisch von verschiedenen Azulenvorstufen zu enthalten, deren Komponenten in wechselnder Menge vorhanden sind. Eine der Komponenten ist identisch mit dem Proazulen der Kamille. Vor etwa 30 Jahren machte Rosenmundl) im Verlauf seiner ArFeiten iiber die Beeinflussung der Wirksamkeit von Katalysatoren die Beobachtung, daB Benzoesaure-benzylester unter geeigneten Bedingungen katalytisch zu Toluol und Benzoesaure hydriert wird :Er teilte ferner mit, dalJ aus Benzoesaure-benzhydrylester in analoger Reaktion Diphenylmethan neben Benzoesaure erhalten wird, wahrend Ester von Phenolen oder aliphatischen Alkoholen sich nicht in entsprechender Weise umsetzen lassen. In einer spateren Arbeit2) wurde gezeigt, daB Phenylbutyrolactone als innere Ester substituierter Benzylalkohole ebenfalls katalytisch sehr leicht zu Phenylbuttersauren reduziert werden : X\ R H 1 RX\\ 1 1-CH-CH2-CH, 7 2 O---

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Über die katalytische Reduktion von Mandelsäuren

Cited by 9 publications

References 0 publications

Multi-Catalytic Route for the Synthesis of (S)-Tembamide

Multi-Catalytic Route for the Synthesis of (S)-Tembamide

Hydrogenolysis of Benzyl Groups Attached to Oxygen, Nitrogen, or Sulfur

Die Umwandlung von Arylcarbinolen in Desoxyverbindungen durch katalytische Reduktion ihrer Ester

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