Catalytic Asymmetric Cyanation Reactions

Kurono, Nobuhito; Ohkuma, Takeshi

doi:10.1021/acscatal.5b02184

Cited by 241 publications

(96 citation statements)

References 190 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A general issue for carboxycyanations has been a significantly lower catalytic activity compared to cyanosilylations, thus requiring catalyst loadings in a range of 1–10 mol % for the best reported systems . This might be partly explained by catalyst inhibition by the Lewis basic carboxy protective groups.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Carboxycyanation of Aldehydes by Cooperative AlF/Onium Salt Catalysts: from Cyanoformate to KCN as Cyanide Source

Brodbeck

Álvarez‐Barcia

Meisner

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

Asymmetric 1,2‐additions of cyanide yield enantioenriched cyanohydrins as versatile chiral building blocks. Next to HCN, volatile organic cyanide sources are usually used. Among them, cyanoformates are more attractive on technical scale than TMSCN for cost reasons, but catalytic productivity is usually lower. Here, the development of a new strategy for cyanations is described, in which this activity disadvantage is overcome. A Lewis acidic Al center cooperates with an aprotic onium moiety within a remarkably robust bifunctional Al–F–salen complex. This allowed for unprecedented turnover numbers of up to 104. DFT studies suggest an unexpected unique trimolecular pathway in which the ammonium bound cyanide attacks the aldehyde, which itself is activated by the carbonyl group of the cyanoformate binding to the Al center. In addition, a novel practical carboxycyanation method was developed that makes use of KCN as the sole cyanide source. The use of a pyrocarbonate as carboxylating reagent provided the best results.

show abstract

Section: Introductionmentioning

confidence: 99%

Asymmetric Carboxycyanation of Aldehydes by Cooperative AlF/Onium Salt Catalysts: from Cyanoformate to KCN as Cyanide Source

Brodbeck

Álvarez‐Barcia

Meisner

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…For all the solvents tested, much lower selectivities were obtained compared to toluene. 2 Determined by HPLC after hydrolysis to the free cyanohydrin (-)-1c.…”

Section: Resultsmentioning

confidence: 99%

“…Different approaches have been developed for the preparation of chiral cyanohydrins, but the selective addition of a cyanide source to a carbonyl compound is the most common procedure. Several types of catalysts have been described for this selective process, including metal catalysts, biocatalysts or organocatalysts [2,3].…”

Section: Introductionmentioning

confidence: 99%

Organocatalyzed synthesis of optically active cyanohydrins starting from alpha-ketoesters

Gonzalo

2017

Proceedings of the 21st International Electronic Conference on Synthetic Organic Chemistry

View full text Add to dashboard Cite

Abstract:The synthesis of highly functionalized optically active cyanohydrins is described by performing the organocatalyzed selective addition of trimethylsilyl cyanide to a set of alpha-ketoesters employing different (thio)ureas as hydrogen bond catalysts. By optimizing certain parameters that affect to the organocatalytic process, as the temperature, solvent or cyanide concentration, it is possible to obtain the corresponding chiral cyanohydrins with excellent conversions and moderate to good optical purities.

show abstract

“…B3, Scheme 24) in oxime ligation in aqueous solution through formation of intermediate iminium salt, followed by transimination by the oxime (Scheme 29) [196][197][198]. Since the pioneering work of Oguni and co-workers in 1993 that used the chiral Schiff base 56 and Ti(O-i-Pr)4 as the catalyst (Scheme 30) [199], a large number of enantioselective syntheses of cyanohydrins have been developed [200][201][202][203][204]. The transition structure 57 has been proposed to interpret the results (mech.…”

Section: σ-And π-Nucleophiles As Catalysts For Nucleophilic Additionsmentioning

confidence: 99%

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

et al. 2016

View full text Add to dashboard Cite

Catalysis fulfills the promise that high-yielding chemical transformations will require little energy and produce no toxic waste. This message is carried by the study of the evolution of molecular catalysis of some of the most important reactions in organic chemistry. After reviewing the conceptual underpinnings of catalysis, we discuss the applications of different catalysts according to the mechanism of the reactions that they catalyze, including acyl group transfers, nucleophilic additions and substitutions, and C-C bond forming reactions that employ umpolung by nucleophilic additions to C=O and C=C double bonds. We highlight the utility of a broad range of organocatalysts other than compounds based on proline, the cinchona alkaloids and binaphthyls, which have been abundantly reviewed elsewhere. The focus is on organocatalysts, although a few examples employing metal complexes and enzymes are also included due to their significance. Classical Brønsted acids have evolved into electrophilic hands, the fingers of which are hydrogen donors (like enzymes) or other electrophilic moieties. Classical Lewis base catalysts have evolved into tridimensional, chiral nucleophiles that are N-(e.g., tertiary amines), P-(e.g., tertiary phosphines) and C-nucleophiles (e.g., N-heterocyclic carbenes). Many efficient organocatalysts bear electrophilic and nucleophilic moieties that interact simultaneously or not with both the electrophilic and nucleophilic reactants. A detailed understanding of the reaction mechanisms permits the design of better catalysts. Their construction represents a molecular science in itself, suggesting that sooner or later chemists will not only imitate Nature but be able to catalyze a much wider range of reactions with high chemo-, regio-, stereo-and enantioselectivity. Man-made organocatalysts are much smaller, cheaper and more stable than enzymes.

show abstract

Catalytic Asymmetric Cyanation Reactions

Cited by 241 publications

References 190 publications

Asymmetric Carboxycyanation of Aldehydes by Cooperative AlF/Onium Salt Catalysts: from Cyanoformate to KCN as Cyanide Source

Asymmetric Carboxycyanation of Aldehydes by Cooperative AlF/Onium Salt Catalysts: from Cyanoformate to KCN as Cyanide Source

Organocatalyzed synthesis of optically active cyanohydrins starting from alpha-ketoesters

Organocatalysis: Fundamentals and Comparisons to Metal and Enzyme Catalysis

Contact Info

Product

Resources

About