Darstellung und stereoselektive Reaktionen von (<i>R</i>)‐α‐Sulfonyloxynitrilen

Effenberger, Franz; Stelzer, Uwe

doi:10.1002/ange.19911030728

Cited by 21 publications

(3 citation statements)

References 20 publications

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“…The Lewis acid catalyzed cyanosilylation reaction of aldehydes was chosen to study the catalytic activity of the two frameworks (Scheme 1). [10] Both PKU-1 and PKU-2 were first washed with water at 40 8C for four hours to remove the remaining boric acid species from the pores. [10] Both PKU-1 and PKU-2 were first washed with water at 40 8C for four hours to remove the remaining boric acid species from the pores.…”

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confidence: 99%

“…[8,9] In this transformation, highly versatile cyanohydrin trimethylsilyl ethers are produced, which can be readily converted into important compounds such as a-hydroxycarboxylic acids or bamino alcohols. [10] Both PKU-1 and PKU-2 were first washed with water at 40 8C for four hours to remove the remaining boric acid species from the pores. After filtration, the samples were dried under vacuum at 110 8C for another four hours.…”

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confidence: 99%

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Microporous Aluminoborates with Large Channels: Structural and Catalytic Properties

Yang

Bartoszewicz

et al. 2011

Angew Chem Int Ed

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Channel zapping: PKU-1 and newly synthesized PKU-2 (Al(2)B(5)O(9)(OH)(3)⋅n H(2)O; see picture) possess microporous structures with 18-ring and 24-ring channels, respectively. They show high reactivity and size selectivity in the cyanosilylation of aldehydes as heterogeneous Lewis acid catalysts. The different channel sizes determine the substrate selectivity. These examples demonstrate the potential of octahedron-based aluminoborate channels in catalysis.

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confidence: 99%

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confidence: 99%

Microporous Aluminoborates with Large Channels: Structural and Catalytic Properties

Yang

Bartoszewicz

et al. 2011

Angew Chem Int Ed

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“…The thus activated cyanohydrins (R)-S react with complete inversion of configuration with various nucleophiles [12]. with potassium acetate in DMF at room temperature the cyanohydrin acetates (S)-6 are obtained in excellent yields.…”

Section: Transformations Of the Nitrile Group Of (R)-cyanohydrinsmentioning

confidence: 99%

(R)- and (S)-Cyanohydrins - Their Enzymatic Synthesis and Their Reactions

Effenberger

1992

Microbial Reagents in Organic Synthesis

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ABSTRACT. The known enzymes (R)-and (S)-oxynitrilase catalyze the enantioselective addition of hydrocyanic acid to aldehydes to give (R)-and (S)-cyanohydrins. The optical yields can distinctly be improved by the application of organic solvents (i.e. ethyl acetate or diisopropyl ether) instead of a waterjethanol mixture which was used previously in these reactions. For the enzyme (S)-oxynitrilase Sorghum bicolor evolved to be the best source. The optically active cyanohydrins can be transformed without any racemization by acid catalyzed hydrolysis into a-hydroxy acids and by hydrogenation with lithiumjaluminum hydride into 1,2-amino alcohols. Via addition of Grignard reagents to the O-protected cyanohydrins and follow-up hydrogenation, 1,2-amino alcohols are gained with very high diastereoselectivity. By O-sulfonylation of the (R)-and (S)-cyanohydrins optically active a-sulfonyloxy nitriles are obtained. These nitriles react with various nucleophiles by complete inversion of configuration to form various a-substituted carboxylic acid derivatives, a-azido nitriles, a-amino nitriles, aamino acids, etc. Enzyme cata1yzed preparation of (R)-cyanohydrinsE. Pfeil et al. have investigated the (R)-oxynitrilase (E.C. 4.1.2.10) catalyzed addition of hydrocyanic acid to various aldehydes to give (R)-cyanohydrins [1]. In the applied solvents, water or waterjalcohol mixtures, the normal chemical addition of HCN cannot be avoided which results in pure optical yields in most cases. All efforts to improve the optical yields in waterjalcohol solutions failed. By using organie solvents, which are not miscible with water, however, the (R)-cyanohydrins are obtained in excellent chemical and optical yields [2]. 25 S. Servi (ed.), Microbia l Reagents in Organic Synthesis,[25][26][27][28][29][30][31][32][33]

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Formation of CC Bonds: Enzymatic Synthesis of Cyanohydrins

Fechter¹,

Griengl²

2002

Enzyme Catalysis in Organic Synthesis

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Darstellung und stereoselektive Reaktionen von (R)‐α‐Sulfonyloxynitrilen

Cited by 21 publications

References 20 publications

Microporous Aluminoborates with Large Channels: Structural and Catalytic Properties

Microporous Aluminoborates with Large Channels: Structural and Catalytic Properties

(R)- and (S)-Cyanohydrins - Their Enzymatic Synthesis and Their Reactions

Formation of CC Bonds: Enzymatic Synthesis of Cyanohydrins

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