Eine nahezu ideale asymmetrische Autokatalyse mit (2-Alkinyl-5-pyrimidyl)alkanolen

Shibata, Takanori; Yonekubo, Shigeru; Soai, Kenso

doi:10.1002/(sici)1521-3757(19990301)111:5<746::aid-ange746>3.0.co;2-3

Cited by 36 publications

(2 citation statements)

References 15 publications

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“…Comparison of the investigated 5,5’‐disubstituted BIPHEP oxides with 3,3’‐disubstituted analogues enables detailed insight into substitution pattern effects on the Gibbs free energy Δ G ╪ and the activation parameters Δ H ╪ and Δ S ╪ . Another advantage of tropos ligands is their potentially applicability in self‐amplifying enantioselective processes …”

Section: Introductionmentioning

confidence: 99%

The Stereodynamics of 5,5’‐Disubstituted BIPHEPs

Maier

Trapp

2012

Chirality

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We investigated the stereodynamics of 5,5'-substituted tropos BIPHEP ligands (2,2'-bis(diphenylphosphino)-biphenyls) by enantioselective dynamic high-performance liquid chromatography (DHPLC) to elucidate the influence of the substitution pattern and electronics of the substituents (methyl, methoxy, and hydroxyl groups). By temperature-dependent dynamic HPLC measurements the activation parameters ΔG(╪), ΔH(╪), and ΔS(╪) could be determined with high precision, revealing that the activation barrier of these 5,5'-substituted BIPHEP ligands ranges in a narrow band between 87.8 and 93.0 kJ mol(-1), making them highly attractive as deracemizable dynamic chiral ligands in asymmetric catalysis. Interestingly, the activation parameters are highly influenced by a hydroxyl or methoxy group in the 5,5'-position of the BIPHEP ligands.

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Section: Introductionmentioning

confidence: 99%

The Stereodynamics of 5,5’‐Disubstituted BIPHEPs

Maier

Trapp

2012

Chirality

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“…We previously reported that 2-(alkylethynyl)- and 2-(trialkylsilylethynyl)pyrimidine-5-carbaldehyde[ 15 ] serve as excellent substrates in asymmetric autocatalysis with the amplification of enantiomeric excess. [ 16 ] Thus, as an achiral substrate, we selected 2-( tert -butyldimethylsilylethynyl)pyrimidine-5-carbaldehyde ( 1 ), which can be prepared from 5-bromo-2-iodopyrimidine by a coupling reaction with tert -butyldimethylsilylacetylene and formylation (see the Supporting Information).…”

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confidence: 99%

Enantioselective CC Bond Formation as a Result of the Oriented Prochirality of an Achiral Aldehyde at the Single‐Crystal Face upon Treatment with a Dialkyl Zinc Vapor

et al. 2011

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Show your best face: An achiral pyrimidine‐5‐carbaldehyde that forms an achiral crystal (${{{\rm P}\bar 1}}$) with enantiotopic (001) and (${{00\bar 1}}$) faces underwent enantioselective addition of iPr2Zn to the single exposed enantiotopic surface to give highly enantiomerically enriched S and R secondary alcohols (see scheme). The absolute configuration of the alcohol product correlated with the orientation of the prochiral aldehyde in the achiral crystal lattice.

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Asymmetric Synthesis of an Organic Compound with High Enantiomeric Excess Induced by Inorganic Ionic Sodium Chlorate

2000

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Recent progress in asymmetric synthesis has been made by the developments of both organic asymmetric catalysts and stoichiometric organic chiral auxiliaries. [1] The origin of significant enantiomeric enrichments in organic compounds such as l-amino acids on the earth has been an intriguing puzzle. [2] One of the proposed mechanisms for the enantiomeric enrichments of organic compounds is through asymmetric synthesis and/or subsequent asymmetric adsorption [3] on the surface of inorganic enantiomorphic crystals. We recently reported an enantioselective synthesis of an organic compound promoted by chiral quartz, [4] which is an enantiomorphic inorganic molecule with covalent bonds between the silicon and oxygen atoms.On the other hand, sodium chlorate (NaClO 3 ) is an enantiomorphic inorganic ionic crystal. [5] Kondepudi et al. reported that almost all of the NaClO 3 crystals precipitated from a stirred particular solution have the same chirality. [6,7] However, the relevance of the chirality of NaClO 3 to that of an organic compound was not established. An earlier report [8] on the enantioselective adsorption of racemic compounds by NaClO 3 was disproved by the later examination of Gillard and da Luz de Jesus. [9] Thus, the question has remained as to whether significantly enantiomerically enriched organic compound can be formed using chiral NaClO 3 , an inorganic ionic crystal.Herein we report an unprecedented highly enantioselective synthesis of an organic compound which is induced by d-or l-NaClO 3 crystals. The enantioselective addition of diisopropylzinc (iPr 2 Zn) to 2-(tert-butylethynyl)pyrimidine-5-carbaldehyde (1) in the presence of d-or l-NaClO 3 powder gave pyrimidylalkanol 2 with high ee values (96 ± 98 % ee) in high yields (90 ± 99 %; Scheme 1, Table 1).The (S)-pyrimidylalkanol (S)-2 was obtained with 98 % ee in 93 % yield when iPr 2 Zn was added to the mixture of d-NaClO 3 and aldehyde 1 (Entry 1). The reaction is reproducible (Entries 2 and 3). On the other hand, reactions between aldehyde 1 and iPr 2 Zn in the presence of l-NaClO 3 , instead of d-NaClO 3 , always gave (R)-2 with 98 % ee in yields of 91 ± 98 % (Entries 4 ± 6). When the reactions were run sequentially in the presence of d-, l-, d-, and l-NaClO 3 , using exactly the same reaction equipments

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Eine nahezu ideale asymmetrische Autokatalyse mit (2-Alkinyl-5-pyrimidyl)alkanolen

Cited by 36 publications

References 15 publications

The Stereodynamics of 5,5’‐Disubstituted BIPHEPs

The Stereodynamics of 5,5’‐Disubstituted BIPHEPs

Enantioselective CC Bond Formation as a Result of the Oriented Prochirality of an Achiral Aldehyde at the Single‐Crystal Face upon Treatment with a Dialkyl Zinc Vapor

Asymmetric Synthesis of an Organic Compound with High Enantiomeric Excess Induced by Inorganic Ionic Sodium Chlorate

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