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11 pages, 6146 KiB

Open AccessCommunication

The Reduction of Carbonyl Compounds with Dicyclopentylzinc: A New Example of Asymmetric Amplifying Autocatalysis

by Elena Sh. Saigitbatalova, Liliya Z. Latypova, Almaz A. Zagidullin, Almira R. Kurbangalieva and Ilya D. Gridnev

Int. J. Mol. Sci. 2023, 24(23), 17048; https://doi.org/10.3390/ijms242317048 - 1 Dec 2023

Cited by 2 | Viewed by 1652

Abstract

A previously unknown reduction of carbonyl compounds with dicyclopentylzinc is reported. Aldehydes react in mild conditions yielding corresponding primary alcohols and cyclopentene. Although cyclohexanone and acetophenone are inert to dicyclopentylzinc, a variety of heterocyclic ketones reacted readily, yielding reasonable to high yields of corresponding secondary alcohols. When the reaction was catalyzed with (–)-(1R,2S)-ephedrine, 3-acetylpyridine (10) resulted in a high yield of (S)-1-(pyridin-3-yl)ethanol (19) with >99% ee. 5-Acetyl-2-bromopyridine (11) also provided the corresponding optically active alcohol 20, albeit with a much lower optical yield. When 10% of 19 with 92% ee was used as an autocatalyst, 55% yield of the same compound was obtained, with 95% ee and 96% ee in two independent experiments. A three-stage reaction sequence starting from “no chirality” reaction yielded 19 with 6% ee. Thus, amplifying autocatalysis was detected in the reaction of ketone 10 with dicylopentylzinc. Full article

(This article belongs to the Special Issue Recent Trends in Stereoselective Synthesis and Chiral Catalysis)

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13 pages, 4897 KiB

Open AccessCommunication

Reaction of Triazolic Aldehydes with Diisopropyl Zinc: Chirality Dissipation versus Amplification

by Oleg A. Mikhaylov, Elena Sh. Saigitbatalova, Liliya Z. Latypova, Almira R. Kurbangalieva and Ilya D. Gridnev

Symmetry 2023, 15(7), 1382; https://doi.org/10.3390/sym15071382 - 7 Jul 2023

Cited by 2 | Viewed by 1412

Abstract

The phenomenon of amplifying asymmetric autocatalysis (AAA) has recently been restricted to alkylation of several specific substrates with diisopropyl zinc (Soai reaction). Targeting the extension of the scope of this phenomenon, we studied the reaction of triazolic aldehydes with diisopropyl zinc. Experiments demonstrated a diversity of results for the dissipation of chirality, conserving the existent ee and spontaneous chirality generation. Computational analysis showed that depending on the level of oligomerization of the catalyst, one could expect amplification (monomeric catalyst) while maintaining the existing chirality (dimeric catalyst) or dissipation of chirality (tetrameric catalyst). These findings are promising for the elaboration of synthetic protocols controlling chirality generation. In addition, three optically active triazolic alcohols were characterized. Full article

(This article belongs to the Special Issue Asymmetric Synthesis: Topics and Advances)

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7 pages, 1219 KiB

Open AccessArticle

London Disperse Interactions Assist Chiral Induction in the Soai Autoamplifying Reaction Provoked by 1- and 2-Aza[6]helicenes

by Roman V. Zonov and Ilya D. Gridnev

Catalysts 2022, 12(8), 859; https://doi.org/10.3390/catal12080859 - 4 Aug 2022

Cited by 2 | Viewed by 1832

Abstract

In this paper, DFT computations revealed the mechanisms of the asymmetric catalytic reactions of diisopropylzinc with pyrimidylaldehyde catalyzed by 1- and 2-aza[6]helicenes, which make them effective inductors of the autocatalytic chiral amplification Soai reaction. The generation of chirality takes place through the formation of adducts of aldehyde and helicenes stabilized via non-covalent disperse interactions strictly defining the orientation of the aldehyde molecule in the corresponding transition state. Full article

(This article belongs to the Special Issue State-of-the-Art in Asymmetric Organocatalysis)

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20 pages, 3398 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Role of Asymmetric Autocatalysis in the Elucidation of Origins of Homochirality of Organic Compounds

by Kenso Soai, Tsuneomi Kawasaki and Arimasa Matsumoto

Symmetry 2019, 11(5), 694; https://doi.org/10.3390/sym11050694 - 20 May 2019

Cited by 27 | Viewed by 5851

Abstract

Pyrimidyl alkanol and related compounds were found to be asymmetric autocatalysts in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde and related aldehydes. In the asymmetric autocatalysis with amplification of enantiomeric excess (ee), the very low ee (ca. 0.00005%) of 2-alkynyl-5-pyrimidyl alkanol was significantly amplified to >99.5% ee with an increase in the amount. By using asymmetric autocatalysis with amplification of ee, several origins of homochirality have been examined. Circularly polarized light, chiral quartz, and chiral crystals formed from achiral organic compounds such as glycine and carbon (¹³C/¹²C), nitrogen (¹⁵N/¹⁴N), oxygen (¹⁸O/¹⁶O), and hydrogen (D/H) chiral isotopomers were found to act as the origin of chirality in asymmetric autocatalysis. And the spontaneous absolute asymmetric synthesis was also realized without the intervention of any chiral factor. Full article

(This article belongs to the Special Issue Possible Scenarios for Homochirality on Earth)

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13 pages, 1345 KiB

Open AccessArticle

Natural Abundance Isotopic Chirality in the Reagents of the Soai Reaction

by Béla Barabás, Róbert Kurdi and Gyula Pályi

Symmetry 2016, 8(1), 2; https://doi.org/10.3390/sym8010002 - 8 Jan 2016

Cited by 13 | Viewed by 5959

Abstract

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. Full article

(This article belongs to the Special Issue Asymmetric Catalysis)

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32 pages, 590 KiB

Open AccessReview

The Role of Stochastic Models in Interpreting the Origins of Biological Chirality

by Gábor Lente

Symmetry 2010, 2(2), 767-798; https://doi.org/10.3390/sym2020767 - 12 Apr 2010

Cited by 45 | Viewed by 7278

Abstract

This review summarizes recent stochastic modeling efforts in the theoretical research aimed at interpreting the origins of biological chirality. Stochastic kinetic models, especially those based on the continuous time discrete state approach, have great potential in modeling absolute asymmetric reactions, experimental examples of which have been reported in the past decade. An overview of the relevant mathematical background is given and several examples are presented to show how the significant numerical problems characteristic of the use of stochastic models can be overcome by non-trivial, but elementary algebra. In these stochastic models, a particulate view of matter is used rather than the concentration-based view of traditional chemical kinetics using continuous functions to describe the properties system. This has the advantage of giving adequate description of single-molecule events, which were probably important in the origin of biological chirality. The presented models can interpret and predict the random distribution of enantiomeric excess among repetitive experiments, which is the most striking feature of absolute asymmetric reactions. It is argued that the use of the stochastic kinetic approach should be much more widespread in the relevant literature. Full article

(This article belongs to the Special Issue Symmetry of Life and Homochirality)

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