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Special Issue "Asymmetric Synthesis"

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Synthesis".

Deadline for manuscript submissions: closed (15 December 2009)

Special Issue Editor

Guest Editor
Dr. Noureddine Khiar

Instituto de Investigaciones Químicas, C.S.I.C-Universidad de Sevilla, c/. Am rico Vespucio, s/n., Isla de la Cartuja, 41092 Sevilla, Spain
Website | E-Mail
Fax: +34 95 446 05 65
Interests: Stereoselectivity, Chiral Pool, Chiral Auxiliary, Asymmetric Catalysis, Enzyme Catalysis, Transition metal Catalysis, Organocatalysis

Keywords

  • stereoselectivity
  • chiral pool
  • chiral auxiliary
  • asymmetric catalysis
  • dnzyme catalysis
  • transition metal catalysis
  • organocatalysis

Published Papers (9 papers)

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Research

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Open AccessArticle From Symmetric Glycerol Derivatives to Dissymmetric Chlorohydrins
Molecules 2011, 16(3), 2065-2074; doi:10.3390/molecules16032065
Received: 9 December 2010 / Revised: 16 February 2011 / Accepted: 28 February 2011 / Published: 2 March 2011
Cited by 4 | PDF Full-text (146 KB)
Abstract
The anticipated worldwide increase in biodiesel production will result in an accumulation of glycerol for which there are insufficient conventional uses. The surplus of this by-product has increased rapidly during the last decade, prompting a search for new glycerol applications. We describe here
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The anticipated worldwide increase in biodiesel production will result in an accumulation of glycerol for which there are insufficient conventional uses. The surplus of this by-product has increased rapidly during the last decade, prompting a search for new glycerol applications. We describe here the synthesis of dissymmetric chlorohydrin esters from symmetric 1,3-dichloro-2-propyl esters obtained from glycerol. We studied the influence of two solvents: 1,4-dioxane and 1-butanol and two bases: sodium carbonate and 1-butylimidazole, on the synthesis of dissymmetric chlorohydrin esters. In addition, we studied the influence of other bases (potassium and lithium carbonates) in the reaction using 1,4-dioxane as the solvent. The highest yield was obtained using 1,4-dioxane and sodium carbonate. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
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Open AccessArticle A General and Simple Diastereoselective Reduction by L-Selectride: Efficient Synthesis of Protected (4S,5S)-Dihydroxy Amides
Molecules 2010, 15(4), 2771-2781; doi:10.3390/molecules15042771
Received: 18 December 2009 / Revised: 24 March 2010 / Accepted: 12 April 2010 / Published: 16 April 2010
Cited by 2 | PDF Full-text (194 KB)
Abstract
A general approach to (4S,5S)-4-benzyloxy-5-hydroxy-N-(4-methoxybenzyl) amides 10 based on a diastereoselective reduction of (5S,6RS)-6-alkyl-5-benzyloxy-6-hydroxy-2-piperidinones 6 and their tautomeric ring-opened keto amides 7 is described. The reduction with L-Selectride at -20 °C to
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A general approach to (4S,5S)-4-benzyloxy-5-hydroxy-N-(4-methoxybenzyl) amides 10 based on a diastereoselective reduction of (5S,6RS)-6-alkyl-5-benzyloxy-6-hydroxy-2-piperidinones 6 and their tautomeric ring-opened keto amides 7 is described. The reduction with L-Selectride at -20 °C to room temperature afforded the products 10 in excellent yields and moderate to high syn-diastereoselectivities. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
Open AccessArticle Organocatalytic Michael Addition of 1,3-Dicarbonyl Indane Compounds to Nitrostyrenes
Molecules 2010, 15(4), 2551-2563; doi:10.3390/molecules15042551
Received: 9 December 2009 / Revised: 3 March 2010 / Accepted: 19 March 2010 / Published: 12 April 2010
Cited by 10 | PDF Full-text (315 KB)
Abstract
To map out the efficient organocatalyst requirements in the Michael addition of 1,3-dicarbonyl indane compounds to nitrostyrenes, a dozen different amino organocatalysts containing a p-toluenesulfonyl group (Ts) have been evaluated; excellent enantio-selectivities (up to er 92:8) were obtained with a primary amine-based
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To map out the efficient organocatalyst requirements in the Michael addition of 1,3-dicarbonyl indane compounds to nitrostyrenes, a dozen different amino organocatalysts containing a p-toluenesulfonyl group (Ts) have been evaluated; excellent enantio-selectivities (up to er 92:8) were obtained with a primary amine-based Ts-DPEN catalyst and a plausible catalytic reaction mechanism was proposed on the basis of the experimental results. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
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Open AccessArticle Synthesis and Conformational Study of a Novel Macrocyclic Chiral(Salen) ligand and its Uranyl and Mn Complexes
Molecules 2010, 15(3), 1442-1452; doi:10.3390/molecules15031442
Received: 21 December 2009 / Revised: 20 January 2010 / Accepted: 2 March 2010 / Published: 9 March 2010
Cited by 6 | PDF Full-text (446 KB)
Abstract
A novel chiral macrocyclic ligand incorporating a chiral salen moiety into a framework containing two biphenyl units was synthesized. Structural properties and conformational aspects of the free ligand and an UO2 complex were studied by using NMR spectroscopy in solution and MM
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A novel chiral macrocyclic ligand incorporating a chiral salen moiety into a framework containing two biphenyl units was synthesized. Structural properties and conformational aspects of the free ligand and an UO2 complex were studied by using NMR spectroscopy in solution and MM calculations. The Mn(III) complex was tested as catalyst in enantioselective oxidation of prochiral unfunctionalized olefins to the corresponding optically active epoxides under very mild conditions. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
Open AccessArticle Protecting-Group-Free Synthesis of 2-Deoxy-Aza-Sugars
Molecules 2009, 14(12), 5298-5307; doi:10.3390/molecules14125298
Received: 13 November 2009 / Revised: 15 December 2009 / Accepted: 15 December 2009 / Published: 16 December 2009
Cited by 18 | PDF Full-text (197 KB)
Abstract
The protecting-group-free asymmetric synthesis of 1,2,4-trideoxy-1,4-imino-L-xylitol is readily achieved in five steps from 2-deoxy-D-ribose and with an overall yield of 48%. Key in this synthesis is the application of our recently developed Vasella-reductive amination and carbamate annulation methodologies to the synthesis of 2-deoxy-aza-sugars.
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The protecting-group-free asymmetric synthesis of 1,2,4-trideoxy-1,4-imino-L-xylitol is readily achieved in five steps from 2-deoxy-D-ribose and with an overall yield of 48%. Key in this synthesis is the application of our recently developed Vasella-reductive amination and carbamate annulation methodologies to the synthesis of 2-deoxy-aza-sugars. The carbamate annulation occurred with excellent yield and diastereoselectively (>20:1 d.r.), in favour of the 3,4-cis isomer. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
Open AccessArticle A Striking Exception to the Chelate Model for Acyclic Diastereocontrol: Efficient Access to a Versatile Propargyl Alcohol for Chemical Synthesis
Molecules 2009, 14(12), 5216-5222; doi:10.3390/molecules14125216
Received: 26 October 2009 / Revised: 17 November 2009 / Accepted: 30 November 2009 / Published: 15 December 2009
Cited by 5 | PDF Full-text (236 KB)
Abstract
The four-step, asymmetric synthesis of a chiral propargyl alcohol 1 from (R)-pantolactone is described. A key feature of the synthesis is a diastereoselective acetylide addition to a chiral α-alkoxy-aldehyde 7, in which unusual Felkin selectivity is observed, despite the potential
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The four-step, asymmetric synthesis of a chiral propargyl alcohol 1 from (R)-pantolactone is described. A key feature of the synthesis is a diastereoselective acetylide addition to a chiral α-alkoxy-aldehyde 7, in which unusual Felkin selectivity is observed, despite the potential for chelation control. Crystalline propargyl alcohol 1 is valuable for complex molecule synthesis, and is easy to prepare in multi-gram quantities and high diastereomeric purity. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
Open AccessArticle Asymmetric Friedel-Crafts Alkylation of Indole with Chalcones Catalyzed by Chiral Phosphoric Acids
Molecules 2009, 14(8), 3030-3036; doi:10.3390/molecules14083030
Received: 22 July 2009 / Revised: 6 August 2009 / Accepted: 10 August 2009 / Published: 13 August 2009
Cited by 18 | PDF Full-text (292 KB) | HTML Full-text | XML Full-text
Abstract
The reaction of indole with chalcones, to give Michael-type adducts, was found to occur with good efficiency (up to 98% yield) and moderate enantioselectivity (up to 52% e.e.) in the presence of a chiral BINOL-based phosphoric acid. Furthermore, the alkylation products can be
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The reaction of indole with chalcones, to give Michael-type adducts, was found to occur with good efficiency (up to 98% yield) and moderate enantioselectivity (up to 52% e.e.) in the presence of a chiral BINOL-based phosphoric acid. Furthermore, the alkylation products can be obtained in much higher e.e.s after one only crystallization. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
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Review

Jump to: Research

Open AccessReview Synthetic Applications of Chiral Unsaturated Epoxy Alcohols Prepared by Sharpless Asymmetric Epoxidation
Molecules 2010, 15(2), 1041-1073; doi:10.3390/molecules15021041
Received: 8 January 2010 / Revised: 9 February 2010 / Accepted: 20 February 2010 / Published: 23 February 2010
Cited by 21 | PDF Full-text (1044 KB)
Abstract
An overview of the synthesis and applications of chiral 2,3-epoxy alcohols containing unsaturated chains is presented. One of the fundamental synthetic routes to these compounds is Sharpless asymmetric epoxidation, which is reliable, highly chemoselective and enables easy prediction of the product enantioselectivity. Thus,
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An overview of the synthesis and applications of chiral 2,3-epoxy alcohols containing unsaturated chains is presented. One of the fundamental synthetic routes to these compounds is Sharpless asymmetric epoxidation, which is reliable, highly chemoselective and enables easy prediction of the product enantioselectivity. Thus, unsaturated epoxy alcohols are readily obtained by selective oxidation of the allylic double bond in the presence of other carbon-carbon double or triple bonds. The wide availability of epoxy alcohols with unsaturated chains, the versatility of the epoxy alcohol functionality (e.g. regio- and stereo-selective ring opening; oxidation; and reduction), and the arsenal of established alkene chemistries, make unsaturated epoxy alcohols powerful starting materials for the synthesis of complex targets such as biologically active molecules. The popularization of ring-closing metathesis has further increased their value, making them excellent precursors to cyclic compounds. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
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Open AccessReview Organocatalyzed Asymmetric α-Oxidation, α-Aminoxylation and α-Amination of Carbonyl Compounds
Molecules 2010, 15(2), 917-958; doi:10.3390/molecules15020917
Received: 25 December 2009 / Revised: 27 January 2010 / Accepted: 5 February 2010 / Published: 11 February 2010
Cited by 85 | PDF Full-text (335 KB)
Abstract
Organocatalytic asymmetric α-oxidation and amination reactions of carbonyl compounds are highly useful synthetic methodologies, especially in generating chiral building blocks that previously have not been easily accessible by traditional methods. The concept is relatively new and therefore the list of new catalysts, oxidizing
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Organocatalytic asymmetric α-oxidation and amination reactions of carbonyl compounds are highly useful synthetic methodologies, especially in generating chiral building blocks that previously have not been easily accessible by traditional methods. The concept is relatively new and therefore the list of new catalysts, oxidizing and aminating reagents, as well as new substrates, are expanding at an amazing rate. The scope of this review includes new reactions and catalysts, mechanistic aspects and synthetic applications of α-oxidation, hydroxylation, aminoxylation, amination, hydrazination, hydroxyamination and related α-heteroatom functionalization of aldehydes, ketones and related active methylene compounds published during 2005–2009. Full article
(This article belongs to the Special Issue Asymmetric Synthesis)
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