Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess

Matsumoto, Arimasa; Abe, Takaaki; Hara, Atsushi; Tobita, Takayuki; Sasagawa, Taisuke; Kawasaki, Tsuneomi; Soai, Kenso

doi:10.1002/anie.201508036

Cited by 63 publications

(44 citation statements)

References 111 publications

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“…Initial mechanistic models proposed the catalytically active species to be dimeric, but NMR and microcalorimetry experiments conducted since strongly suggest the catalytically competent assemblies to be at least tetrameric in ligand . Crystallographic studies showed racemic tetramers to be structurally distinct from the enantiopure ones (Figure ), which is likely connected with the reactivity and the unique stereochemical outcomes of this autocatalytic reaction …”

Section: Figurementioning

confidence: 98%

Chiral Inactivation: An Old Phenomenon with a New Twist

Raskatov

2017

Chemistry A European J

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Mixing of enantiomers of chiral molecules can have remarkable effects on the properties of their higher order assemblies. This, in turn, may have profound impact on both structural and functional outcomes, and has been noted across a wide range of contexts. This account presents key examples from organic, organometallic and bioorganic molecular sciences and showcases that, in disciplines as distinct as asymmetric catalysis and racemic protein crystallography, there is a fundamental way in which enantiomers differ from racemates.

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Section: Figurementioning

confidence: 98%

Chiral Inactivation: An Old Phenomenon with a New Twist

Raskatov

2017

Chemistry A European J

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“…In this substructure, four Zn atoms and four O atoms form a virtual cube-like polyhedron, as shown in Figure 3B. Interestingly this hypothetical structural element also appears in the X-ray structure of the "enantiomeric" model compound of the Soai autocatalysis, reported very recently by Matsumoto et al [47]. It should be mentioned that the symmetries of compound S-E4 are valid only if the isotopic composition of the central O2Zn2 ring is disregarded.…”

Section: Zinc Isotopic Chirality?mentioning

confidence: 52%

“…Some fragments of hypothetic intermediates [44][45][46] of the Soai autocatalysis show chiral arrangement of the Zn atoms. One of these fragments, the structure of which has been essentially supported by X-ray crystallography [47], will also be included in the present study. …”

Section: Resultsmentioning

confidence: 99%

“…Reasonable theoretical efforts at the elucidation of the structure of the possible intermediates have been published on the basis of "first principles" and other calculations [44][45][46]49], as well as kinetic/calorimetric/spectroscopic measurements [51,52] (only to mention the most cited ones). Very recently, even realistically designed and prepared model compounds could be crystallized and studied by X-ray crystallography [47]. Several possible intermediates of fairly complicated structures have been proposed.…”

Section: Discussionmentioning

confidence: 99%

“…This is a fundamental difference, especially from the viewpoint that in 2 the i-Pr groups are present before the C-C bond making it an alkylation step, while the i-Pr group in 3 represent a final stage; that is, the stage when the fate of the asymmetry of the critical carbon atom has already been decided. On the other hand, compound 3 appears as autocatalyst in the subsequent cycle(s) of the reaction in intermediate(s), the structure of which is actually known only from theoretical studies [44][45][46][47]49] The analysis of the eventual role of isotopically chiral i-Pr group(s) will be deduced step-by-step starting with the methyl group.…”

Section: The Iso-propyl Group(s)mentioning

confidence: 99%

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Natural Abundance Isotopic Chirality in the Reagents of the Soai Reaction

2016

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Isotopic chirality influences sensitively the enantiomeric outcome of the Soai asymmetric autocatalysis. Therefore magnitude and eventual effects of isotopic chirality caused by natural abundance isotopic substitution (H, C, O, Zn) in the reagents of the Soai reaction were analyzed by combinatorics and probability calculations. Expectable enantiomeric excesses were calculated by the Pars-Mills equation. It has been found that the chiral isotopic species formed by substitution in the otherwise achiral reagents provide enantiomeric excess (e.e.) levels that are higher than the sensitivity threshold of the Soai autocatalysis towards chiral induction. Consequently, possible chiral induction exerted by these e.e. values should be taken into account in considerations regarding the molecular events and the mechanism of the chiral induction in the Soai reaction.

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Asymmetric Induction by a Nitrogen ¹⁴N/¹⁵N Isotopomer in Conjunction with Asymmetric Autocatalysis

et al. 2016

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Chirality arising from isotope substitution, especially with atoms heavier than the hydrogen isotopes,i su sually not considered as ource of chirality in ac hemical reaction. An N 2 ,N 2 ,N 3 ,N 3 -tetramethyl-2,3-butanediamine containing nitrogen ( 14 N/ 15 N) isotope chirality was synthesized and it was revealed that this isotopically chiral diamine compound acts as ac hiral initiator for asymmetric autocatalysis. Most of the chemical elements have stable isotopes.Isotope-substituted compounds (isotopomers) have almost the same chemical reactivity,isotope substitution and isotope effect, therefore they are widely used for studies of reaction mechanisms and tracing compounds.[1] However,i sotope substitution sometimes breaks the molecular symmetry and produces hidden chirality in usually achiral molecules. Usually,this hidden chirality does not receive much attention because the difference between these isotopically chiral compounds is very small and negligible in asymmetric induction. Although the chirality arising from isotope substitution was discussed after the finding of stable isotopomers, [2][3][4] the isotope effect in chirality has mainly been studied on hydrogen isotopes because the almost double relative mass ratio of Ha nd Dp roduces relatively large isotope effects compared with other element isotopomers.[5] Thus,c hirality induction in areaction arising from heavier atoms [6] is ahighly challenging and interesting topic, especially in the study of the origin of homochirality. [7] We have been studying asymmetric autocatalysis of pyrimidyl alkanol, [8] which causes significant amplification of enantiomeric excess (ee)during the progress of areaction. This reaction can recognize the various chiral environments [9] and attracts wide attention from the viewpoint of symmetry breaking [10] and its unique reaction mechanism.[11] Recently, we demonstrated that asubtle difference of isotopic chirality can induce asymmetric induction in an asymmetric autocatalysis reaction.[12] Chiral compounds (as the result of hydrogen (H/D), [13] carbon ( 12 C/ 13 C), [14] and oxygen ( 16 O/ 18 O) [15] isotopes) act as chiral initiators for asymmetric autocatalysis. Herein, we report the first example of asymmetric induction by chiral nitrogen ( 14 N/ 15 N) isotopomers with as maller relative mass difference compared to previously reported isotopomers (Scheme 1).Nitrogen is one of the abundant atoms in the construction of various bioorganic molecules,and the coordinating ability of nitrogen atoms is widely exploited in various ligands. 15 Nis auseful NMR-active isotope and the isotope ratio of 14 N/ 15 N is also used in the study of the origin of meteorites. [16] However,t oo ur knowledge,i sotopically chiral compounds arising from nitrogen isotope ( 14 N/ 15 N) substitution have not been synthesized and studied as achiral initiator.Herein, we demonstrate the synthesis of compounds that are isotopically chiral by nitrogen isotope substitution and their chiral induction of asymmetric autocatalysis (S...

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Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess

Cited by 63 publications

References 111 publications

Chiral Inactivation: An Old Phenomenon with a New Twist

Chiral Inactivation: An Old Phenomenon with a New Twist

Natural Abundance Isotopic Chirality in the Reagents of the Soai Reaction

Asymmetric Induction by a Nitrogen ¹⁴N/¹⁵N Isotopomer in Conjunction with Asymmetric Autocatalysis

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Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess

Cited by 63 publications

References 111 publications

Chiral Inactivation: An Old Phenomenon with a New Twist

Chiral Inactivation: An Old Phenomenon with a New Twist

Natural Abundance Isotopic Chirality in the Reagents of the Soai Reaction

Asymmetric Induction by a Nitrogen 14N/15N Isotopomer in Conjunction with Asymmetric Autocatalysis

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Asymmetric Induction by a Nitrogen ¹⁴N/¹⁵N Isotopomer in Conjunction with Asymmetric Autocatalysis