A Designed Amide as an Aldol Donor in the Direct Catalytic Asymmetric Aldol Reaction

Weidner, Karin; Kumagai, Naoya; Shibasaki, Masakatsu

doi:10.1002/ange.201403118

Cited by 21 publications

(2 citation statements)

References 33 publications

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“…Scattered examplesd ocument CÀN s bond-cleavager eactions in twisted amides of types V and VI under reductive, oxidative, anda lkylative conditions, as reported by the Aube [18,19] and Szostak [20,21] groups.T he pK a of the aCÀHb ondt ot he carbonyl group is dramatically lowered, and as ar esult of amide nitrogenp yramidalization in VII,i ts use in aldol additions is enabled. [22,23] Similar effects were observed by Lloyd-Jones and Booker-Milburn in sterically hindereda mides such as VIII, [24] which undergo rapid proton switch via at wisted conformer because of their enhanced aCÀHa cidity.…”

Section: Introductionsupporting

confidence: 74%

Unique Stereoselective Homolytic C−O Bond Activation in Diketopiperazine‐Derived Alkoxyamines by Adjacent Amide Pyramidalization

Amatov

Jangra

Pohl

et al. 2018

Chemistry A European J

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Simple monocyclic diketopiperazine (DKP)-derived alkoxyamines exhibit unprecedented activation of a remote C-O bond for homolysis by amide distortion. The combination of strain-release-driven amide planarization and the persistent radical effect (PRE) enables a unique, irreversible, and quantitative trans→cis isomerization under much milder conditions than typically observed for such homolysis-limited reactions. This isomerization is shown to be general and independent of the steric and electronic nature of both the amino acid side chains and the substituents at the DKP nitrogen atoms. Homolysis rate constants are determined, and they significantly differ for both the labile trans diastereomers and the stable cis diastereomers. To reveal the factors influencing this unusual process, structural features of the kinetic trans diastereomers and thermodynamic cis diastereomers are investigated in the solid state and in solution. X-ray crystallographic analysis and computational studies indicate substantial distortion of the amide bond from planarity in the trans-alkoxyamines, and this is believed to be the cause for the facile and quantitative isomerization. Thus, these amino-acid-derived alkoxyamines are the first examples that exhibit a large thermodynamic preference for one diastereomer over the other upon thermal homolysis, and this allows controlled switching of configurations and configurational cycling.

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Section: Introductionsupporting

confidence: 74%

Unique Stereoselective Homolytic C−O Bond Activation in Diketopiperazine‐Derived Alkoxyamines by Adjacent Amide Pyramidalization

Amatov

Jangra

Pohl

et al. 2018

Chemistry A European J

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“…The initial discoveryw as made with a-sulfanyla mide 32 a,w hich was anticipated to exhibit ah igh coordinationa ptitude to chiral soft Lewis acid catalysts (Scheme8). [24] The cooperative action of the AgBF 4 /(R,R)-Ph-BPE 33/LiOAr (BPE = 1,2-bis(2,5-diphenylphospholano)ethane;A r = p-MeOC 6 H 4 )c atalytic system,i n which AgBF 4 /(R,R)-Ph-BPE 33 functions as as oft Lewis acid to activate 32 a ford eprotonation by LiOAr as aB rønsted base, promoted the directa symmetric aldol reaction. LiOTf was essentialt os uppress the formation of an insoluble aggregate of AgBF 4 /(R,R)-Ph-BPE 33 in THF that was not catalytically competent.…”

Section: -Azaindoline Amidesmentioning

confidence: 99%

ChemInform Abstract: Nucleophilic and Electrophilic Activation of Non‐Heteroaromatic Amides in Atom‐Economical Asymmetric Catalysis

Kumagai

Shibasaki

2016

ChemInform

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Synthesis of α‐Alkyl‐β‐Hydroxy Amides through Biocatalytic Dynamic Kinetic Resolution Employing Alcohol Dehydrogenases

et al. 2019

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Chiral (α-substituted) β-hydroxy amides are interesting derivatives as they are useful building blocks of many biologically active compounds. Herein, the biocatalytic stereocontrolled synthesis of various acyclic syn-α-alkyl-β-hydroxy amides through a dynamic kinetic resolution is shown. Hence, a series of overexpressed alcohol dehydrogenases (ADHs) in Escherichia coli was used to reduce the corresponding racemic β-keto amides. Among them, ADH-A from Rhodococcus ruber and commercial evo-1.1.200 afforded the best activities and selectivities, giving access to the opposite enantiomers with high diastereomeric excess and excellent enantiomeric excess. Some of these compounds were obtained at semipreparative scale.

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A Designed Amide as an Aldol Donor in the Direct Catalytic Asymmetric Aldol Reaction

Cited by 21 publications

References 33 publications

Unique Stereoselective Homolytic C−O Bond Activation in Diketopiperazine‐Derived Alkoxyamines by Adjacent Amide Pyramidalization

Unique Stereoselective Homolytic C−O Bond Activation in Diketopiperazine‐Derived Alkoxyamines by Adjacent Amide Pyramidalization

ChemInform Abstract: Nucleophilic and Electrophilic Activation of Non‐Heteroaromatic Amides in Atom‐Economical Asymmetric Catalysis

Synthesis of α‐Alkyl‐β‐Hydroxy Amides through Biocatalytic Dynamic Kinetic Resolution Employing Alcohol Dehydrogenases

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