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Special Issue "Stereoselective Synthesis"

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

Deadline for manuscript submissions: closed (31 July 2012)

Special Issue Editor

Guest Editor
Prof. Dr. Marcelo Daniel Preite (Website)

Facultad de Quimica, Pontificia Universidad Catolica de Chile, VicuñaMackenna 4860, Casilla 306, 6904411 Santiago, Chile
Phone: +56-2-3544426
Fax: +56 2 354 4744
Interests: total synthesis; stereoselective synthesis; asymmetric synthesis; chiral auxiliaries and catalysts; main-group in synthesis

Special Issue Information

Dear Colleagues,

Stereoselective synthesis, also known as asymmetric synthesis, is a very wide concept, that includes any form of synthesis using reactions in which at least one element of chirality is formed in a substrate molecule, producing stereoisomeric, either enantio- or diastereoisomeric products, in unequal amounts. This special issue of Molecules will consider any submissions associated with stereoselective syntheses in any form.

Prof. Dr. Marcelo D. Preite

Guest Editor

Keywords

  • asymmetric synthesis
  • catalytic asymmetric synthesis
  • chiral auxiliaries
  • stoichiometric asymmetric synthesis
  • enantioselectivity
  • diastereoselectivity

Published Papers (4 papers)

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Research

Open AccessArticle Chiral Zn(II)-Bisamidine Complex as a Lewis-Brønsted Combined Acid Catalyst: Application to Asymmetric Mukaiyama Aldol Reactions of α-Ketoesters
Molecules 2012, 17(8), 9010-9022; doi:10.3390/molecules17089010
Received: 11 July 2012 / Revised: 21 July 2012 / Accepted: 21 July 2012 / Published: 30 July 2012
Cited by 4 | PDF Full-text (967 KB) | XML Full-text | Supplementary Files
Abstract
Focusing on the steric and electronic properties of the resonance-stabilized amidine framework, a cationic metal-bisamidine complex was designed as a conjugated combined Lewis-Brønsted acid catalyst. The chiral Zn(II)-bisamidine catalyst prepared from the 2,2'-bipyridyl derived bisamidine ligand, ZnCl2, and AgSbF6 [...] Read more.
Focusing on the steric and electronic properties of the resonance-stabilized amidine framework, a cationic metal-bisamidine complex was designed as a conjugated combined Lewis-Brønsted acid catalyst. The chiral Zn(II)-bisamidine catalyst prepared from the 2,2'-bipyridyl derived bisamidine ligand, ZnCl2, and AgSbF6 promoted asymmetric Mukaiyama aldol reaction of α-ketoester and α,α-disubstituted silyl enol ether to afford the α-hydroxyester having sequential quarternary carbons in good yield, albeit with low enantioselectivity. Addition of 1.0 equivalent of the fluoroalcohol having suitable acidity and bulkiness dramatically increased the enantioselectivity (up to 68% ee). DFT calculations suggested that this additive effect would be caused by self-assembly of the fluoroalcohol on the Zn(II)-bisamidine catalyst. Full article
(This article belongs to the Special Issue Stereoselective Synthesis)
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Open AccessArticle A Further Contribution to the Study of Sagittamide A: Synthesis of a Pivotal Intermediate Belonging to a Rare L-Series
Molecules 2012, 17(7), 7709-7721; doi:10.3390/molecules17077709
Received: 3 May 2012 / Revised: 13 June 2012 / Accepted: 18 June 2012 / Published: 25 June 2012
PDF Full-text (477 KB)
Abstract A key saggitamide intermediate corresponding to a rare sugar framework has been obtained. This approach should help to establish the overall configuration of more complex structures of the sagittamide family. Full article
(This article belongs to the Special Issue Stereoselective Synthesis)
Open AccessCommunication Ring Cleavage Reactions of Methyl α-D-Allopyranoside Derivatives with Phenylboron Dichloride and Triethylsilane
Molecules 2011, 16(12), 10303-10313; doi:10.3390/molecules161210303
Received: 31 October 2011 / Revised: 25 November 2011 / Accepted: 5 December 2011 / Published: 13 December 2011
PDF Full-text (379 KB)
Abstract
In the course of our studies on the regioselective carbon-oxygen bond cleavage of the benzylidene acetal group of hexopyranosides with a reducing agent, we found that a combination of a Lewis acid and a reducing agent triggered a ring-opening reaction of the [...] Read more.
In the course of our studies on the regioselective carbon-oxygen bond cleavage of the benzylidene acetal group of hexopyranosides with a reducing agent, we found that a combination of a Lewis acid and a reducing agent triggered a ring-opening reaction of the pyranose ring of methyl α-D-allopyranosides. The formation of an acyclic boronate ester by the attachment of a hydride ion at C-1 indicated that the unexpected endocyclic cleavage of the bond between the anomeric carbon atom and the pyranose ring oxygen atom proceeded via an oxacarbenium ion intermediate produced by the chelation between O5/O6 of the pyranoside and the Lewis acid, followed by nucleophile substitution with a hydride ion at C1. Full article
(This article belongs to the Special Issue Stereoselective Synthesis)
Figures

Open AccessArticle Synthesis of New Substituted Chromen[4,3-c]pyrazol-4-ones and Their Antioxidant Activities
Molecules 2011, 16(12), 10292-10302; doi:10.3390/molecules161210292
Received: 11 November 2011 / Revised: 28 November 2011 / Accepted: 29 November 2011 / Published: 12 December 2011
Cited by 15 | PDF Full-text (245 KB)
Abstract
A series of new coumarin derivatives 4 containing a 4-arylbut-3-en-2-one moiety were synthesized by condensation of 3-acetylcoumarin 1 with aryl aldehydes 2 in chloroform in the presence of piperidine. The interactions of 3-formyl-4-chlorocoumarin (3) with nitrogen-containg nucleophiles leading to the [...] Read more.
A series of new coumarin derivatives 4 containing a 4-arylbut-3-en-2-one moiety were synthesized by condensation of 3-acetylcoumarin 1 with aryl aldehydes 2 in chloroform in the presence of piperidine. The interactions of 3-formyl-4-chlorocoumarin (3) with nitrogen-containg nucleophiles leading to the corresponding substituted chromen-[4,3-c]pyrazol-4-ones 5 are described. The structures of the obtained compounds were established on the basis of 1D NMR, 2D NMR and IR and further the compounds were evaluated for possible antioxidant activities. The coumarinic chalcone 4a has been found to be the most active (IC50 = 2.07 μM) in this study. Full article
(This article belongs to the Special Issue Stereoselective Synthesis)

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