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Special Issue "Asymmetric Catalysis"

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A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (30 April 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Takashi Ohshima (Website)

Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi Higashi-ku, Fukuoka 812-8582, Japan
Interests: Lewis acid catalysis; Lewis base catalysit; transition metal catalysis; organocatalysis; enzymatic reaction; multifunctional catalysis; green chemistry

Special Issue Information

Dear Colleagues,

In biological systems, the two enantiomers, in many cases, have a different response. Thus, most of the new drugs reaching the market today are single enantiomers, rather than the racemic mixtures. In addition, nonracemic molecules also contribute to the creation of advanced materials. The synthesis of chiral organic compounds in a highly enantioselective manner is therefore of great importance. In the earliest stages of development, the creation of the chiral center is made possible thanks to chiral substrate, auxiliary, or stoichiometric amounts of chiral reagents. Since the discovery of homogeneous catalytic asymmetric hydrogenation reactions, a variety of highly efficient catalytic asymmetric reactions have been developed so far and research in asymmetric catalysis achieved prominence in both academic and industrial laboratories. Although some of asymmetric catalyses have reached a high level of selectivity and efficiency, interest in further improvements continues to grow period. This special issue of Molecules will highlight all areas of current and future interest, reflecting the tremendous expansion in the scope of the asymmetric catalysis.

I strongly encourage authors to submit their work to this special issue of Molecules.

Prof. Dr. Takashi Ohshima
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).

Published Papers (13 papers)

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Research

Jump to: Review

Open AccessArticle Enantio- and Periselective Nitroalkene Diels-Alder Reactions Catalyzed by Helical-Chiral Hydrogen Bond Donor Catalysts
Molecules 2013, 18(8), 9982-9998; doi:10.3390/molecules18089982
Received: 15 July 2013 / Revised: 13 August 2013 / Accepted: 14 August 2013 / Published: 19 August 2013
PDF Full-text (623 KB) | HTML Full-text | XML Full-text
Abstract
Helical-chiral double hydrogen bond donor catalysts promote the nitroalkene Diels-Alder reaction in an enantio- and periselective manner. This represents the first asymmetric catalytic nitroalkene Diels-Alder reaction via LUMO-lowering catalysis. To gain an insight into this new process, the substrate scope of our [...] Read more.
Helical-chiral double hydrogen bond donor catalysts promote the nitroalkene Diels-Alder reaction in an enantio- and periselective manner. This represents the first asymmetric catalytic nitroalkene Diels-Alder reaction via LUMO-lowering catalysis. To gain an insight into this new process, the substrate scope of our catalyst was investigated by exploiting readily available 5-substituted pentamethylcyclopentadienes. The catalyst was found to tolerate dienes with different steric demands as well as dienes substituted with heteroatoms. The synthetic utility of 5-substituted pentamethylcyclopentadienes is rather limited, and thus we have developed a three-step route to 1,4,5,5-tetrasubstituted cyclopentadienes from commercially available ketones. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
Open AccessArticle Mirror-Symmetry-Breaking in Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-biphenyl] (PF8P2) is Susceptible to Terpene Chirality, Achiral Solvents, and Mechanical Stirring
Molecules 2013, 18(6), 7035-7057; doi:10.3390/molecules18067035
Received: 13 May 2013 / Revised: 3 June 2013 / Accepted: 3 June 2013 / Published: 17 June 2013
Cited by 8 | PDF Full-text (2464 KB) | HTML Full-text | XML Full-text
Abstract
Solvent chirality transfer of (S)-/(R)-limonenes allows the instant generation of optically active PF8P2 aggregates with distinct circular dichroism (CD)/circularly polarized luminescence (CPL) amplitudes with a high quantum yield of 16–20%. The present paper also reports subtle mirror-symmetry-breaking effects [...] Read more.
Solvent chirality transfer of (S)-/(R)-limonenes allows the instant generation of optically active PF8P2 aggregates with distinct circular dichroism (CD)/circularly polarized luminescence (CPL) amplitudes with a high quantum yield of 16–20%. The present paper also reports subtle mirror-symmetry-breaking effects in CD-/CPL-amplitude and sign, CD/UV-vis spectral wavelengths, and photodynamics of the aggregates, though the reasons for the anomaly are unsolved. However, these photophysical properties depend on (i) the chemical natures of chiral and achiral molecules when used in solvent quantity, (ii) clockwise and counterclockwise stirring operations, and (iii) the order of addition of limonene and methanol to the chloroform solution. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessArticle Application Scope and Limitations of TADDOL-Derived Chiral Ammonium Salt Phase-Transfer Catalysts
Molecules 2013, 18(4), 4357-4372; doi:10.3390/molecules18044357
Received: 25 March 2013 / Revised: 8 April 2013 / Accepted: 11 April 2013 / Published: 12 April 2013
Cited by 6 | PDF Full-text (448 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We have recently introduced a new class of chiral ammonium salt catalysts derived from easily available TADDOLs. To get a full picture of the scope of application and limitations of our catalysts we tested them in a variety of different important transformations. [...] Read more.
We have recently introduced a new class of chiral ammonium salt catalysts derived from easily available TADDOLs. To get a full picture of the scope of application and limitations of our catalysts we tested them in a variety of different important transformations. We found that, although these compounds have recently shown their good potential in the asymmetric α-alkylation of glycine Schiff bases, they clearly failed when we attempted to control more reactive nucleophiles like b-keto esters. On the other hand, when using them to catalyse the addition of glycine Schiff bases to different Michael acceptors it was found necessary to carefully optimize the reaction conditions for every single substrate class, as seemingly small structural changes sometimes required the use of totally different reaction conditions. Under carefully optimized conditions enantiomeric ratios up to 91:9 could be achieved in the addition of glycine Schiff bases to acrylates, whereas acrylamides and methyl vinyl ketone gave slightly lower selectivities (up to e.r. 77:23 in these cases). Thus, together with additional studies towards the syntheses of these catalysts we have now a very detailed understanding about the scope and limitations of the synthesis sequence to access our PTCs and about the application scope of these catalysts in asymmetric transformations. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessArticle Synthesis of Main-Chain Chiral Quaternary Ammonium Polymers for Asymmetric Catalysis Using Quaternization Polymerization
Molecules 2012, 17(6), 7569-7583; doi:10.3390/molecules17067569
Received: 27 April 2012 / Revised: 4 June 2012 / Accepted: 13 June 2012 / Published: 19 June 2012
Cited by 10 | PDF Full-text (365 KB)
Abstract
Main-chain chiral quaternary ammonium polymers were successfully synthesized by the quaternization polymerization of cinchonidine dimer with dihalides. The polymerization occurred smoothly under optimized conditions to give novel type of main-chain chiral quaternary ammonium polymers. The catalytic activity of the polymeric chiral organocatalysts [...] Read more.
Main-chain chiral quaternary ammonium polymers were successfully synthesized by the quaternization polymerization of cinchonidine dimer with dihalides. The polymerization occurred smoothly under optimized conditions to give novel type of main-chain chiral quaternary ammonium polymers. The catalytic activity of the polymeric chiral organocatalysts was investigated on the asymmetric benzylation of N-(diphenylmethylidene)glycine tert-butyl ester. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessCommunication Enantioselective Michael Addition of 3-Aryl-Substituted Oxindoles to Methyl Vinyl Ketone Catalyzed by a Binaphthyl-Modified Bifunctional Organocatalyst
Molecules 2012, 17(6), 7523-7532; doi:10.3390/molecules17067523
Received: 2 May 2012 / Revised: 6 June 2012 / Accepted: 14 June 2012 / Published: 18 June 2012
Cited by 21 | PDF Full-text (234 KB)
Abstract
The enantioselective conjugate addition reaction of 3-aryl-substituted oxindoles with methyl vinyl ketone promoted by binaphthyl-modified bifunctional organocatalysts was investigated. The corresponding Michael adducts, containing a quaternary center at the C3-position of the oxindoles, were generally obtained in high yields with excellent enantioselectivities [...] Read more.
The enantioselective conjugate addition reaction of 3-aryl-substituted oxindoles with methyl vinyl ketone promoted by binaphthyl-modified bifunctional organocatalysts was investigated. The corresponding Michael adducts, containing a quaternary center at the C3-position of the oxindoles, were generally obtained in high yields with excellent enantioselectivities (up to 91% ee). Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessArticle A New Method for Production of Chiral 2-Aryl-2-fluoropropanoic Acids Using an Effective Kinetic Resolution of Racemic 2-Aryl-2-fluoropropanoic Acids
Molecules 2012, 17(6), 7356-7378; doi:10.3390/molecules17067356
Received: 2 May 2012 / Revised: 4 June 2012 / Accepted: 8 June 2012 / Published: 14 June 2012
Cited by 5 | PDF Full-text (606 KB) | Supplementary Files
Abstract
We report a new method for the preparation of chiral 2-aryl-2-fluoropropanoic acids, including 2-fluoroibuprofen, a fluorinated analogue of non-steroidal anti-inflammatory drugs (NSAIDs), by the kinetic resolution of racemic 2-aryl-2-fluoropropanoic acids using enantioselective esterification. By applying pivalic anhydride (Piv2O) as a [...] Read more.
We report a new method for the preparation of chiral 2-aryl-2-fluoropropanoic acids, including 2-fluoroibuprofen, a fluorinated analogue of non-steroidal anti-inflammatory drugs (NSAIDs), by the kinetic resolution of racemic 2-aryl-2-fluoropropanoic acids using enantioselective esterification. By applying pivalic anhydride (Piv2O) as a coupling agent, bis(α-naphthyl)methanol [(α-Np)2CHOH] as an achiral alcohol, and (+)-benzotetramisole (BTM) as a chiral acyl-transfer catalyst, a series of racemic 2-aryl-2-fluoropropanoic acids were kinetically separated to afford the optically active carboxylic acids and the corresponding esters with good to high enantiomeric excesses. This technology can provide a convenient approach to furnish the chiral α-fluorinated drugs containing quaternary carbons at the α-positions in the 2-aryl-2-fluoropropanoic acid structure. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessArticle Cooperative Al(Salen)-Pyridinium Catalysts for the Asymmetric Synthesis of trans-Configured β-Lactones by [2+2]-Cyclocondensation of Acylbromides and Aldehydes: Investigation of Pyridinium Substituent Effects
Molecules 2012, 17(6), 7121-7150; doi:10.3390/molecules17067121
Received: 26 April 2012 / Revised: 23 May 2012 / Accepted: 4 June 2012 / Published: 12 June 2012
Cited by 15 | PDF Full-text (544 KB)
Abstract
The trans-selective catalytic asymmetric formation of β-lactones constitutes an attractive surrogate for anti-aldol additions. Recently, we have reported the first catalyst which is capable of forming trans-β-lactones with high enantioselectivity from aliphatic (and aromatic) aldehyde substrates by cyclocondensation with [...] Read more.
The trans-selective catalytic asymmetric formation of β-lactones constitutes an attractive surrogate for anti-aldol additions. Recently, we have reported the first catalyst which is capable of forming trans-β-lactones with high enantioselectivity from aliphatic (and aromatic) aldehyde substrates by cyclocondensation with acyl bromides. In that previous study the concepts of Lewis acid and organic aprotic ion pair catalysis were combined in a salen-type catalyst molecule. Since a pyridinium residue on the salen periphery is essential for high trans- and enantioselectivity, we were interested in the question of whether substituents on the pyridinium rings could be used to further improve the catalyst efficiency, as they might have a significant impact on the effective charges within the heterocycles. In the present study we have thus compared a small library of aluminum salen/bispyridinium catalysts mainly differing in the substituents on the pyridinium residues. As one result of these studies a new catalyst was identified which offers slightly superior stereoselectivity as compared to the previously reported best catalyst. NBO calculations have revealed that the higher stereoselectivity can arguably not be explained by the variation of the effective charge. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessArticle Catalytic Asymmetric Hydrogenation of 3-Substituted Benzisoxazoles
Molecules 2012, 17(6), 6901-6915; doi:10.3390/molecules17066901
Received: 17 April 2012 / Revised: 2 June 2012 / Accepted: 4 June 2012 / Published: 6 June 2012
Cited by 8 | PDF Full-text (342 KB)
Abstract
A variety of 3-substituted benzisoxazoles were reduced with hydrogen using the chiral ruthenium catalyst, {RuCl(p-cymene)[(R,R)-(S,S)-PhTRAP]}Cl. The ruthenium-catalyzed hydrogenation proceeded in high yield in the presence of an acylating agent, affording a-substituted [...] Read more.
A variety of 3-substituted benzisoxazoles were reduced with hydrogen using the chiral ruthenium catalyst, {RuCl(p-cymene)[(R,R)-(S,S)-PhTRAP]}Cl. The ruthenium-catalyzed hydrogenation proceeded in high yield in the presence of an acylating agent, affording a-substituted o-hydroxybenzylamines with up to 57% ee. In the catalytic transformation, the N–O bond of the benzisoxazole substrate is reductively cleaved by the ruthenium complex under the hydrogenation conditions. The C–N double bond of the resulting imine is saturated stereoselectively through the PhTRAP–ruthenium catalysis. The hydrogenation produces chiral primary amines, which may work as catalytic poisons, however, the amino group of the hydrogenation product is rapidly acylated when the reaction is conducted in the presence of an appropriate acylating agent, such as Boc2O or Cbz-OSu. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
Open AccessCommunication Chiral Bis(Imidazolidine)Pyridine-Cu Complex-Catalyzed Enantioselective [3+2]-Cycloaddition of Azomethine Imines with Propiolates
Molecules 2012, 17(5), 6170-6178; doi:10.3390/molecules17056170
Received: 27 April 2012 / Revised: 18 May 2012 / Accepted: 21 May 2012 / Published: 24 May 2012
Cited by 25 | PDF Full-text (284 KB)
Abstract [3+2] Cycloaddition of azomethine imines with electron-deficient terminal alkynes was smoothly catalyzed by a chiral bis(imidazolidine)pyridine-CuOAc complex to give bicyclic pyrazolo[1,2-a]pyrazolone derivatives with up to 74% ee. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessArticle Chiral Aminophosphines as Catalysts for Enantioselective Double-Michael Indoline Syntheses
Molecules 2012, 17(5), 5626-5650; doi:10.3390/molecules17055626
Received: 23 March 2012 / Revised: 19 April 2012 / Accepted: 23 April 2012 / Published: 11 May 2012
Cited by 7 | PDF Full-text (638 KB)
Abstract
The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient acetylenes is an efficient process for the synthesis of many nitrogen-containing heterocycles. Because the resulting heterocycles contain at least one stereogenic center, this double-Michael reaction would be even more useful if an asymmetric variant [...] Read more.
The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient acetylenes is an efficient process for the synthesis of many nitrogen-containing heterocycles. Because the resulting heterocycles contain at least one stereogenic center, this double-Michael reaction would be even more useful if an asymmetric variant of the reaction were to be developed. Aminophosphines can also facilitate the double-Michael reaction and chiral amines are more readily available in Nature and synthetically; therefore, in this study we prepared several new chiral aminophosphines. When employed in the asymmetric double-Michael reaction between ortho-tosylamidophenyl malonate and 3-butyn-2-one, the chiral aminophosphines produced indolines in excellent yields with moderate asymmetric induction. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
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Open AccessArticle Enantioselective Synthesis of 2,2-Disubstituted Terminal Epoxides via Catalytic Asymmetric Corey-Chaykovsky Epoxidation of Ketones
Molecules 2012, 17(2), 1617-1634; doi:10.3390/molecules17021617
Received: 16 December 2011 / Revised: 23 January 2012 / Accepted: 31 January 2012 / Published: 7 February 2012
Cited by 7 | PDF Full-text (396 KB)
Abstract
Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li3-BINOL complex (LLB) is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in [...] Read more.
Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li3-BINOL complex (LLB) is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (97%–91% ee) and yield ( > 99%–88%) from a broad range of methyl ketones with 1–5 mol% catalyst loading. Enantioselectivity was strongly dependent on the steric hindrance, and other ketones, such as ethyl ketones and propyl ketones resulted in slightly lower enantioselectivity (88%–67% ee). Full article
(This article belongs to the Special Issue Asymmetric Catalysis)

Review

Jump to: Research

Open AccessReview Practical Aspects and Mechanism of Asymmetric Hydrogenation with Chiral Half-Sandwich Complexes
Molecules 2013, 18(6), 6804-6828; doi:10.3390/molecules18066804
Received: 1 May 2013 / Revised: 27 May 2013 / Accepted: 4 June 2013 / Published: 10 June 2013
Cited by 18 | PDF Full-text (495 KB) | HTML Full-text | XML Full-text
Abstract
This review is oriented toward the asymmetric transfer hydrogenation (ATH) of imines regarding mostly fundamental, yet important topics from the practical point of view. Development of analytical methods for the monitoring of ATH (i.e., kinetics and stereoselectivity) belongs to those [...] Read more.
This review is oriented toward the asymmetric transfer hydrogenation (ATH) of imines regarding mostly fundamental, yet important topics from the practical point of view. Development of analytical methods for the monitoring of ATH (i.e., kinetics and stereoselectivity) belongs to those topics, as well as studies on the influence of reaction conditions and structural variations on the reaction performance. The second part is devoted to the reaction mechanism with the emphasis on imine ATH and catalyst behaviour under acidic conditions. The review also addresses the asymmetric hydrogenation (AH) of ketones and imines using molecular hydrogen and the application of ATH in pharmaceutical projects. The contributions of our group to each area are included. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)
Open AccessReview Asymmetric Palladium-Catalysed Intramolecular Wacker-Type Cyclisations of Unsaturated Alcohols and Amino Alcohols
Molecules 2013, 18(6), 6173-6192; doi:10.3390/molecules18066173
Received: 28 April 2013 / Revised: 20 May 2013 / Accepted: 20 May 2013 / Published: 24 May 2013
Cited by 9 | PDF Full-text (320 KB) | HTML Full-text | XML Full-text
Abstract
The palladium (II)-catalysed reactions of alkenols and aminoalkenols such as oxycarbonylations or bicyclisations are powerful methods for the construction of oxygen and nitrogen-containing heterocyclic compounds. This review highlights recent progress in the development of the asymmetric palladium(II)-catalysed Wacker-type cyclisations of unsaturated polyols [...] Read more.
The palladium (II)-catalysed reactions of alkenols and aminoalkenols such as oxycarbonylations or bicyclisations are powerful methods for the construction of oxygen and nitrogen-containing heterocyclic compounds. This review highlights recent progress in the development of the asymmetric palladium(II)-catalysed Wacker-type cyclisations of unsaturated polyols and aminoalcohols. The scope, limitations, and applications of these reactions are presented. Full article
(This article belongs to the Special Issue Asymmetric Catalysis)

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