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Topical Collection "Recent Advances in Organocatalysis"

A topical collection in Molecules (ISSN 1420-3049). This collection belongs to the section "Organic Synthesis".

Editor

Collection Editor
Prof. Dr. Raquel P. Herrera

Laboratorio de Organocatálisis Asimétrica, Departamento de Química Orgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH) CSIC-Universidad de Zaragoza, C/Pedro Cerbuna 12, Zaragoza 50009, Spain
Website | E-Mail
Interests: Asymmetric catalysis, Biological properties, Cinchona, Computational calculations, Hydrogen bond, Mechanistic studies, Natural products, Organic synthesis, Phase transfer catalysts, Squaramides, (Thio)ureas

Topical Collection Information

Dear Colleagues,

The field of organocatalysis has been experiencing an impressive growth in the last decade, and has attracted increasing the interest of researchers due to its broad spectrum of possibilities of activation. This growth has been reflected in the very large number of impressive results achieved with the development of new organocatalytic systems, as well as new and interesting applications. This amazing field of research covers different kind of organocatalysts, such as chiral secondary amines, thioureas, chiral phosphoric acids, squaramides, cinchona alkaloids, or phase transfer catalysts, as the more prominent ones. All of them provide efficient and environmentally friendly access to enantiomerically enriched compounds, including many drugs and bioactive natural products. In this Collection, we want to compile some of the last results reached in each family of organocatalysts by experts in the field.

Dr. Raquel P. Herrera
Collection Editor

Manuscript Submission Information

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Keywords

  • organocatalyst
  • enamine catalysis
  • iminium catalysis
  • phase transfer catalysis
  • H-bond catalysis
  • organocatalysis
  • organocatalytic asymmetric reactions
  • thioureas
  • secondary amines
  • cinchona alkaloids
  • quaternary ammonium salt

Published Papers (18 papers)

2017

Jump to: 2016, 2015

Open AccessArticle Novel Chiral Bis-Phosphoramides as Organocatalysts for Tetrachlorosilane-Mediated Reactions
Molecules 2017, 22(12), 2181; doi:10.3390/molecules22122181 (registering DOI)
Received: 5 October 2017 / Revised: 30 November 2017 / Accepted: 5 December 2017 / Published: 8 December 2017
PDF Full-text (1688 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The formation of novel chiral bidentate phosphoroamides structures able to promote Lewis base-catalyzed Lewis acid-mediated reactions was investigated. Two different classes of phosphoroamides were synthetized: the first class presents a phthalic acid/primary diamine moiety, designed with the aim to perform a self-assembly recognition
[...] Read more.
The formation of novel chiral bidentate phosphoroamides structures able to promote Lewis base-catalyzed Lewis acid-mediated reactions was investigated. Two different classes of phosphoroamides were synthetized: the first class presents a phthalic acid/primary diamine moiety, designed with the aim to perform a self-assembly recognition process through hydrogen bonds; the second one is characterized by the presence of two phosphoroamides as side arms connected to a central pyridine unit, able to chelate SiCl4 in a 2:1 adduct. These species were tested as organocatalysts in the stereoselective allylation of benzaldehyde and a few other aromatic aldehydes with allyl tributyltin in the presence of SiCl4 with good results. NMR studies confirm that only pyridine-based phosphoroamides effectively coordinate tetrachlorosilane and may lead to the generation of a self-assembled entity that would act as a promoter of the reaction. Although further work is necessary to clarify and confirm the formation of the hypothesized adduct, the study lays the foundation for the design and the synthesis of chiral supramolecular organocatalysts. Full article
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Figure 1

Open AccessFeature PaperReview Non-Covalent Organocatalyzed Domino Reactions Involving Oxindoles: Recent Advances
Molecules 2017, 22(10), 1636; doi:10.3390/molecules22101636
Received: 16 September 2017 / Revised: 25 September 2017 / Accepted: 26 September 2017 / Published: 29 September 2017
Cited by 1 | PDF Full-text (7199 KB) | HTML Full-text | XML Full-text
Abstract
The ubiquitous presence of spirooxindole architectures with several functionalities and stereogenic centers in bioactive molecules has been appealing for the development of novel methodologies seeking their preparation in high yields and selectivities. Expansion and refinement in the field of asymmetric organocatalysis have made
[...] Read more.
The ubiquitous presence of spirooxindole architectures with several functionalities and stereogenic centers in bioactive molecules has been appealing for the development of novel methodologies seeking their preparation in high yields and selectivities. Expansion and refinement in the field of asymmetric organocatalysis have made possible the development of straightforward strategies that address these two requisites. In this review, we illustrate the current state-of-the-art in the field of spirooxindole synthesis through the use of non-covalent organocatalysis. We aim to provide a concise overview of very recent methods that allow to the isolation of unique, densely and diversified spirocyclic oxindole derivatives with high structural diversity via the use of cascade, tandem and domino processes. Full article
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Open AccessArticle Readily Available Chiral Benzimidazoles-Derived Guanidines as Organocatalysts in the Asymmetric α-Amination of 1,3-Dicarbonyl Compounds
Molecules 2017, 22(8), 1333; doi:10.3390/molecules22081333
Received: 25 July 2017 / Revised: 7 August 2017 / Accepted: 9 August 2017 / Published: 11 August 2017
PDF Full-text (1145 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The synthesis and the evaluation as organocatalysts of new chiral guanidines derived from benzimidazoles in the enantioselective α-amination of 1,3-dicarbonyl compounds using di-t-butylazodicarboxylate as aminating agent is herein disclosed. The catalysts are readily synthesized through the reaction of 2-chlorobezimidazole and a
[...] Read more.
The synthesis and the evaluation as organocatalysts of new chiral guanidines derived from benzimidazoles in the enantioselective α-amination of 1,3-dicarbonyl compounds using di-t-butylazodicarboxylate as aminating agent is herein disclosed. The catalysts are readily synthesized through the reaction of 2-chlorobezimidazole and a chiral amine in moderate-to-good yields. Among all of them, those derived from (R)-1-phenylethan-1-amine (1) and (S)-1-(2-naphthyl)ethan-1-amine (3) turned out to be the most efficient for such asymmetric transformation, rendering good-to-high yields and moderate-to-good enantioselectivities for the amination products. Full article
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Open AccessFeature PaperArticle Asymmetric Michael Addition Organocatalyzed by α,β-Dipeptides under Solvent-Free Reaction Conditions
Molecules 2017, 22(8), 1328; doi:10.3390/molecules22081328
Received: 7 June 2017 / Revised: 24 July 2017 / Accepted: 27 July 2017 / Published: 10 August 2017
PDF Full-text (2524 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The application of six novel α,β-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and N-arylmaleimides or nitroolefins is described. With N-arylmaleimides as substrates, the best results were achieved with dipeptide 2 as a catalyst in the
[...] Read more.
The application of six novel α,β-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and N-arylmaleimides or nitroolefins is described. With N-arylmaleimides as substrates, the best results were achieved with dipeptide 2 as a catalyst in the presence of aq. NaOH. Whereas dipeptides 4 and 6 in conjunction with 4-dimethylaminopyridine (DMAP) and thiourea as a hydrogen bond donor proved to be highly efficient organocatalytic systems in the enantioselective reaction between isobutyraldehyde and various nitroolefins. Full article
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Figure 1

2016

Jump to: 2017, 2015

Open AccessArticle Expedient Organocatalytic Syntheses of 4-Substituted Pyrazolidines and Isoxazolidines
Molecules 2016, 21(12), 1655; doi:10.3390/molecules21121655
Received: 9 November 2016 / Revised: 24 November 2016 / Accepted: 28 November 2016 / Published: 1 December 2016
Cited by 1 | PDF Full-text (1699 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The efficient organocatalytic synthesis of heterocyclic systems of biological relevance is a subject of growing interest. We have found that the pyrrolidine/benzoic acid-catalyzed reaction of α-substituted propenals such as methacrolein, 2-benzylpropenal and 2-(n-hexyl)propenal with activated hydrazines takes place in very good
[...] Read more.
The efficient organocatalytic synthesis of heterocyclic systems of biological relevance is a subject of growing interest. We have found that the pyrrolidine/benzoic acid-catalyzed reaction of α-substituted propenals such as methacrolein, 2-benzylpropenal and 2-(n-hexyl)propenal with activated hydrazines takes place in very good yields (83%–99.6%) under very mild conditions to afford 4-substituted pyrazolidin-3-ols (as diastereomer mixtures); subsequent oxidation with PCC affords the corresponding-4-substituted-3-pyrazolidinones in essentially quantitative yields. In a similar way, 4-substituted isoxazolidinones are obtained with N-Cbz-hydroxylamine as a reagent. The use of chiral diarylprolinol trimethylsilyl ethers as catalysts allows the synthesis of several of these compounds in optically active form, in some cases with excellent enantioselectivity (up to 96:4 er). A preliminary evaluation of the biological activity shows that some of these compounds exhibit interesting antibacterial and antifungal activities. Full article
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Open AccessReview Recent Advances in Dynamic Kinetic Resolution by Chiral Bifunctional (Thio)urea- and Squaramide-Based Organocatalysts
Molecules 2016, 21(10), 1327; doi:10.3390/molecules21101327
Received: 29 August 2016 / Revised: 27 September 2016 / Accepted: 30 September 2016 / Published: 14 October 2016
Cited by 3 | PDF Full-text (3133 KB) | HTML Full-text | XML Full-text
Abstract
The organocatalysis-based dynamic kinetic resolution (DKR) process has proved to be a powerful strategy for the construction of chiral compounds. In this feature review, we summarized recent progress on the DKR process, which was promoted by chiral bifunctional (thio)urea and squaramide catalysis via
[...] Read more.
The organocatalysis-based dynamic kinetic resolution (DKR) process has proved to be a powerful strategy for the construction of chiral compounds. In this feature review, we summarized recent progress on the DKR process, which was promoted by chiral bifunctional (thio)urea and squaramide catalysis via hydrogen-bonding interactions between substrates and catalysts. A wide range of asymmetric reactions involving DKR, such as asymmetric alcoholysis of azlactones, asymmetric Michael–Michael cascade reaction, and enantioselective selenocyclization, are reviewed and demonstrate the efficiency of this strategy. The (thio)urea and squaramide catalysts with dual activation would be efficient for more unmet challenges in dynamic kinetic resolution. Full article
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Open AccessArticle TBD- or PS-TBD-Catalyzed One-Pot Synthesis of Cyanohydrin Carbonates and Cyanohydrin Acetates from Carbonyl Compounds
Molecules 2016, 21(8), 1030; doi:10.3390/molecules21081030
Received: 30 June 2016 / Revised: 27 July 2016 / Accepted: 3 August 2016 / Published: 10 August 2016
PDF Full-text (6520 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyanation reactions of carbonyl compounds with methyl cyanoformate or acetyl cyanide catalyzed by 5 mol % of 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) were examined. Using methyl cyanoformate, the corresponding cyanohydrin carbonates were readily obtained in high yield for aromatic and aliphatic aldehydes and ketones. Similar results
[...] Read more.
Cyanation reactions of carbonyl compounds with methyl cyanoformate or acetyl cyanide catalyzed by 5 mol % of 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) were examined. Using methyl cyanoformate, the corresponding cyanohydrin carbonates were readily obtained in high yield for aromatic and aliphatic aldehydes and ketones. Similar results were obtained when acetyl cyanide was used as the cyanide source. The polymer-supported catalyst, PS-TBD, also acted as a good catalyst for this reaction. PS-TBD was easily recovered and reused with minimal activity loss. Full article
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Open AccessCommunication Organocatalyzed Intramolecular Carbonyl-Ene Reactions
Molecules 2016, 21(6), 713; doi:10.3390/molecules21060713
Received: 2 May 2016 / Revised: 24 May 2016 / Accepted: 27 May 2016 / Published: 31 May 2016
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Abstract
An organocatalyzed intramolecular carbonyl-ene reaction was developed to produce carbocyclic and heterocyclic 5- and 6-membered rings from a citronellal-derived trifluoroketone and a variety of aldehydes. A phosphoramide derivative was found to promote the cyclization of the trifluoroketone, whereas a less acidic phosphoric acid
[...] Read more.
An organocatalyzed intramolecular carbonyl-ene reaction was developed to produce carbocyclic and heterocyclic 5- and 6-membered rings from a citronellal-derived trifluoroketone and a variety of aldehydes. A phosphoramide derivative was found to promote the cyclization of the trifluoroketone, whereas a less acidic phosphoric acid proved to be a superior catalyst for the aldehyde substrates. Full article

2015

Jump to: 2017, 2016

Open AccessReview Enantioselective Cycloaddition Reactions Catalyzed by BINOL-Derived Phosphoric Acids and N-Triflyl Phosphoramides: Recent Advances
Molecules 2015, 20(9), 16103-16126; doi:10.3390/molecules200916103
Received: 20 July 2015 / Revised: 22 August 2015 / Accepted: 28 August 2015 / Published: 3 September 2015
Cited by 12 | PDF Full-text (1356 KB) | HTML Full-text | XML Full-text
Abstract
Over the last several years there has been a huge increase in the development and applications of new efficient organocatalysts for enantioselective pericyclic reactions, which represent one of the most powerful types of organic transformations. Among these processes are cycloaddition reactions (e.g., [3+2];
[...] Read more.
Over the last several years there has been a huge increase in the development and applications of new efficient organocatalysts for enantioselective pericyclic reactions, which represent one of the most powerful types of organic transformations. Among these processes are cycloaddition reactions (e.g., [3+2]; formal [3+3]; [4+2]; vinylogous [4+2] and 1,3-dipolar cycloadditions), which belong to the most utilized reactions in organic synthesis of complex nitrogen- and oxygen-containing heterocyclic molecules. This review presents the breakthrough realized in this field using chiral BINOL-derived phosphoric acids and N-triflyl phosphoramide organocatalysts. Full article
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Open AccessArticle Functionalization of Cyclodextrins with N-Hydroxyphthalimide Moiety: A New Class of Supramolecular Pro-Oxidant Organocatalysts
Molecules 2015, 20(9), 15881-15892; doi:10.3390/molecules200915881
Received: 28 July 2015 / Revised: 22 August 2015 / Accepted: 27 August 2015 / Published: 31 August 2015
Cited by 4 | PDF Full-text (899 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
N-hydroxyphthalimide (NHPI) is an organocatalyst for free-radical processes able to promote the aerobic oxidation of a wide range of organic substrates. In particular, NHPI can catalyze the hydroperoxidation of polyunsaturated fatty acids (PUFA). This property could be of interest for biological applications.
[...] Read more.
N-hydroxyphthalimide (NHPI) is an organocatalyst for free-radical processes able to promote the aerobic oxidation of a wide range of organic substrates. In particular, NHPI can catalyze the hydroperoxidation of polyunsaturated fatty acids (PUFA). This property could be of interest for biological applications. This work reports the synthesis of two β-cyclodextrin derivatives (CD5 and CD6) having a different degree of methylation and bearing a NHPI moiety. These compounds, having different solubility in water, have been successfully tested for the hydroperoxidation of methyl linoleate, chosen as the PUFA model molecule. Full article
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Open AccessCommunication New Organocatalytic Asymmetric Synthesis of Highly Substituted Chiral 2-Oxospiro-[indole-3,4′- (1′,4′-dihydropyridine)] Derivatives
Molecules 2015, 20(9), 15807-15826; doi:10.3390/molecules200915807
Received: 17 July 2015 / Revised: 13 August 2015 / Accepted: 21 August 2015 / Published: 31 August 2015
Cited by 7 | PDF Full-text (1261 KB) | HTML Full-text | XML Full-text
Abstract
Herein, we report our preliminary results concerning the first promising asymmetric synthesis of highly functionalized 2-oxospiro-[indole-3,4′-(1′,4′-dihydropyridine)] via the reaction of an enamine with isatylidene malononitrile derivatives in the presence of a chiral base organocatalyst. The moderate, but promising, enantioselectivity observed (30%–58% ee (enantiomeric
[...] Read more.
Herein, we report our preliminary results concerning the first promising asymmetric synthesis of highly functionalized 2-oxospiro-[indole-3,4′-(1′,4′-dihydropyridine)] via the reaction of an enamine with isatylidene malononitrile derivatives in the presence of a chiral base organocatalyst. The moderate, but promising, enantioselectivity observed (30%–58% ee (enantiomeric excess)) opens the door to a new area of research for the asymmetric construction of these appealing spirooxindole skeletons, whose enantioselective syntheses are still very limited. Full article
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Open AccessReview Experimental and Theoretical Studies in Hydrogen-Bonding Organocatalysis
Molecules 2015, 20(9), 15500-15524; doi:10.3390/molecules200915500
Received: 31 July 2015 / Revised: 14 August 2015 / Accepted: 17 August 2015 / Published: 26 August 2015
Cited by 11 | PDF Full-text (2197 KB) | HTML Full-text | XML Full-text
Abstract
Chiral thioureas and squaramides are among the most prominent hydrogen-bond bifunctional organocatalysts now extensively used for various transformations, including aldol, Michael, Mannich and Diels-Alder reactions. More importantly, the experimental and computational study of the mode of activation has begun to attract considerable attention.
[...] Read more.
Chiral thioureas and squaramides are among the most prominent hydrogen-bond bifunctional organocatalysts now extensively used for various transformations, including aldol, Michael, Mannich and Diels-Alder reactions. More importantly, the experimental and computational study of the mode of activation has begun to attract considerable attention. Various experimental, spectroscopic and calculation methods are now frequently used, often as an integrated approach, to establish the reaction mechanism, the mode of activation or explain the stereochemical outcome of the reaction. This article comprises several case studies, sorted according to the method used in their study. The aim of this review is to give the investigators an overview of the methods currently utilized for mechanistic investigations in hydrogen-bonding organocatalysis. Full article
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Open AccessArticle Enantioselective Solvent-Free Synthesis of 3-Alkyl-3-hydroxy-2-oxoindoles Catalyzed by Binam-Prolinamides
Molecules 2015, 20(7), 12901-12912; doi:10.3390/molecules200712901
Received: 15 June 2015 / Revised: 6 July 2015 / Accepted: 10 July 2015 / Published: 16 July 2015
Cited by 3 | PDF Full-text (801 KB) | HTML Full-text | XML Full-text
Abstract
BINAM-prolinamides are very efficient catalyst for the synthesis of non-protected and N-benzyl isatin derivatives by using an aldol reaction between ketones and isatins under solvent-free conditions. The results in terms of diastereo- and enantioselectivities are good, up to 99% de and 97%
[...] Read more.
BINAM-prolinamides are very efficient catalyst for the synthesis of non-protected and N-benzyl isatin derivatives by using an aldol reaction between ketones and isatins under solvent-free conditions. The results in terms of diastereo- and enantioselectivities are good, up to 99% de and 97% ee, and higher to those previously reported in the literature under similar reaction conditions. A high variation of the results is observed depending on the structure of the isatin and the ketone used in the process. While 90% of ee and 97% ee, respectively, is obtained by using (Ra)-BINAM-l-(bis)prolinamide as catalyst in the addition of cyclohexanone and α-methoxyacetone to free isatin, 90% ee is achieved for the reaction between N-benzyl isatin and acetone using N-tosyl BINAM-l-prolinamide as catalyst. This reaction is also carried out using a silica BINAM-l-prolinamide supported catalyst under solvent-free conditions, which can be reused up to five times giving similar results. Full article
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Open AccessReview The Emergence of Quinone Methides in Asymmetric Organocatalysis
Molecules 2015, 20(7), 11733-11764; doi:10.3390/molecules200711733
Received: 9 June 2015 / Revised: 17 June 2015 / Accepted: 19 June 2015 / Published: 25 June 2015
Cited by 66 | PDF Full-text (1491 KB) | HTML Full-text | XML Full-text
Abstract
Quinone methides (QMs) are highly reactive compounds that have been defined as “elusive” intermediates, or even as a “synthetic enigma” in organic chemistry. Indeed, there were just a handful of examples of their utilization in catalytic asymmetric settings until some years ago. This
[...] Read more.
Quinone methides (QMs) are highly reactive compounds that have been defined as “elusive” intermediates, or even as a “synthetic enigma” in organic chemistry. Indeed, there were just a handful of examples of their utilization in catalytic asymmetric settings until some years ago. This review collects organocatalytic asymmetric reactions that employ QMs as substrates and intermediates, from the early examples, mostly based on stabilized QMs bearing specific substitution patterns, to more recent contributions, which have dramatically expanded the scope of QM chemistry. In fact, it was only very recently that the generation of QMs in situ through strategies compatible with organocatalytic methodologies has been realized. This tactic has finally opened the gate to the full exploitation of these unstable intermediates, leading to a series of remarkable disclosures. Several types of synthetically powerful asymmetric addition and cycloaddition reactions, applicable to a broad range of QMs, are now available. Full article
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Open AccessArticle Microwave-Assisted Resolution of α-Lipoic Acid Catalyzed by an Ionic Liquid Co-Lyophilized Lipase
Molecules 2015, 20(6), 9949-9960; doi:10.3390/molecules20069949
Received: 17 April 2015 / Revised: 18 May 2015 / Accepted: 19 May 2015 / Published: 29 May 2015
Cited by 3 | PDF Full-text (728 KB) | HTML Full-text | XML Full-text
Abstract
The combination of the ionic liquid co-lyophilized lipase and microwave irradiation was used to improve enzyme performance in enantioselective esterification of α-lipoic acid. Effects of various reaction conditions on enzyme activity and enantioselectivity were investigated. Under optimal condition, the highest enantioselectivity (E
[...] Read more.
The combination of the ionic liquid co-lyophilized lipase and microwave irradiation was used to improve enzyme performance in enantioselective esterification of α-lipoic acid. Effects of various reaction conditions on enzyme activity and enantioselectivity were investigated. Under optimal condition, the highest enantioselectivity (E = 41.2) was observed with a high enzyme activity (178.1 μmol/h/mg) when using the ionic liquid co-lyophilized lipase with microwave assistance. Furthermore, the ionic liquid co-lyophilized lipase exhibited excellent reusability under low power microwave. Full article
Open AccessCommunication Highly Diastereoselective Synthesis of Spiropyrazolones
Molecules 2015, 20(5), 8574-8582; doi:10.3390/molecules20058574
Received: 28 April 2015 / Revised: 8 May 2015 / Accepted: 11 May 2015 / Published: 13 May 2015
Cited by 5 | PDF Full-text (857 KB) | HTML Full-text | XML Full-text
Abstract
We report a highly diastereoselective synthesis of spiropyrazolones catalyzed by secondary amines. The reported Michael-Aldol cascade reaction affords the desired spiropyrazolones bearing four chiral centers as a single diastereomer in excellent yields. Full article
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Open AccessArticle Enantioselective Synthesis of cis-Decalins Using Organocatalysis and Sulfonyl Nazarov Reagents
Molecules 2015, 20(4), 6409-6418; doi:10.3390/molecules20046409
Received: 12 March 2015 / Revised: 2 April 2015 / Accepted: 3 April 2015 / Published: 10 April 2015
PDF Full-text (955 KB) | HTML Full-text | XML Full-text
Abstract
The first organocatalytic synthesis of cis-decalins using sulfonyl Nazarov reagents is reported. The Jørgensen’s catalyst directs this highly enantioselective synthesis using different cyclohexenal derivatives. Full article
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Open AccessArticle DNA-Catalyzed Henry Reaction in Pure Water and the Striking Influence of Organic Buffer Systems
Molecules 2015, 20(3), 4136-4147; doi:10.3390/molecules20034136
Received: 5 February 2015 / Revised: 18 February 2015 / Accepted: 27 February 2015 / Published: 4 March 2015
Cited by 3 | PDF Full-text (1375 KB) | HTML Full-text | XML Full-text
Abstract
In this manuscript we report a critical evaluation of the ability of natural DNA to mediate the nitroaldol (Henry) reaction at physiological temperature in pure water. Under these conditions, no background reaction took place (i.e., control experiment without DNA). Both heteroaromatic
[...] Read more.
In this manuscript we report a critical evaluation of the ability of natural DNA to mediate the nitroaldol (Henry) reaction at physiological temperature in pure water. Under these conditions, no background reaction took place (i.e., control experiment without DNA). Both heteroaromatic aldehydes (e.g., 2-pyridinecarboxaldehyde) and aromatic aldehydes bearing strong or moderate electron-withdrawing groups reacted satisfactorily with nitromethane obeying first order kinetics and affording the corresponding β-nitroalcohols in good yields within 24 h. In contrast, aliphatic aldehydes and aromatic aldehydes having electron-donating groups either did not react or were poorly converted. Moreover, we discovered that a number of metal-free organic buffers efficiently promote the Henry reaction when they were used as reaction media without adding external catalysts. This constitutes an important observation because the influence of organic buffers in chemical processes has been traditionally underestimated. Full article
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