Pronounced asymmetric amplification in the aldol condensation of Chan's diene promoted by a Ti(IV)/BINOL complex

Villano, Rosaria; Acocella, Maria Rosaria; Rosa, Margherita De; Soriente, Annunziata; Scettri, Arrigo

doi:10.1016/j.tetasy.2004.06.009

Cited by 41 publications

(24 citation statements)

References 31 publications

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“…[10] The aldol condensation of masked alkylated acetoacetates [Chans diene, 66, Eq. (19)] [79] and O-silyldienolates 67 [Eq. (20)] [80] was promoted by complexes formed between Ti(OiPr) 4 and scalemic binol.…”

Section: Aldol and Mannich Reactionsmentioning

confidence: 99%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

500

273

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There is a need for the preparation of enantiomerically pure compounds for various applications. An efficient approach to achieve this goal is asymmetric catalysis. The chiral catalyst is usually prepared from a chiral auxiliary, which itself is derived from a natural product or by resolution of a racemic precursor. The use of non-enantiopure chiral auxiliaries in asymmetric catalysis seems unattractive to preparative chemists, since the anticipated enantiomeric excess (ee) of the reaction product should be proportional to the ee value of the chiral auxiliary (linearity). In fact, some deviation from linearity may arise. Such nonlinear effects can be rich in mechanistic information and can be synthetically useful (asymmetric amplification). This Review documents the advances made during the last decade in the use of nonlinear effects in the area of organometallic and organic catalysis.

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Section: Aldol and Mannich Reactionsmentioning

confidence: 99%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

500

273

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“…[25] Dienolates of this type are extremely reactive and require catalyst loadings of only 2 mol % to afford aldol products in high yields and excellent selectivities. To isolate the aldol product in high selectivity, the use of the procedure developed by Carreira and co-workers for cleaving the silyl protecting group in the aldolate intermediate is essential, as racemization of the newly created stereocenter occurs when other methods are employed.…”

Section: Synthetic Equivalents Of Acetoacetate Ester Dianionsmentioning

confidence: 99%

“…The vinylogous aldol reaction of dienolate 21 catalyzed by the Ti(OiPr) 4 /(R)-binol complex; [25] MS = molecular sieves.…”

Section: Synthetic Equivalents Of Acetoacetate Ester Dianionsmentioning

confidence: 99%

Catalytic, Enantioselective, Vinylogous Aldol Reactions

Denmark¹,

Heemstra²,

Beutner³

2005

Angew Chem Int Ed

447

149

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In 1935, R. C. Fuson formulated the principle of vinylogy to explain how the influence of a functional group may be felt at a distant point in the molecule when this position is connected by conjugated double-bond linkages to the group. In polar reactions, this concept allows the extension of the electrophilic or nucleophilic character of a functional group through the pi system of a carbon-carbon double bond. This vinylogous extension has been applied to the aldol reaction by employing "extended" dienol ethers derived from gamma-enolizable alpha,beta-unsaturated carbonyl compounds. Since 1994, several methods for the catalytic, enantioselective, vinylogous aldol reaction have appeared, with which varying degrees of regio- (site), enantio-, and diastereoselectivity can be attained. In this Review, the current scope and limitations of this transformation, as well as its application in natural product synthesis, are discussed.

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“…Das Säurefrag-ment 13 wurde durch eine Titan(IV)-(R)-Binol-katalysierte, vinyloge Aldolreaktion hergestellt, wie sie von Scettri et al entwickelt worden war. [40] Unsere Strategie funktionierte tatsächlich, doch stimmten die 1 H-und 13 Diese Synthese wurde so zum ersten Beispiel für eine Prins-Makrocyclisierung in der Naturstoffsynthese im Verlauf von beinahe dreißig Jahren. Die Effizienz dieser Syntheseroute, die durch den Makrocyclisierungansatz möglich wurde, erwies sich als besonders nützlich, als die Frage nach der Konfiguration der publizierten Neopeltolidstruktur aufkam.…”

Section: Totalsynthese Von Neopeltolid Nach Scheidt Et Alunclassified

Die Prins‐Makrocyclisierung als effiziente Ringschluss‐Strategie in der Naturstoffsynthese

Crane¹,

Scheidt²

2010

Angewandte Chemie

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Prins‐Makrocyclisierungen haben sich in jüngster Zeit als gute Methode für die Synthese natürlicher Polyketidderivate bewährt. Diese Reaktion stellt eine ökonomische und selektive Methode zur Bildung Tetrahydropyran‐haltiger Makrocyclen verschiedener Größe zur Verfügung und toleriert vielfältige funktionelle Gruppen im Makrocyclus, in der Regel bei guten bis ausgezeichneten Ausbeuten. Nach der erstmaligen Beschreibung der Prins‐Makrocyclisierung im Jahr 1979 wurde es still um diese Methode; erste Anwendungsbeispiele finden sich erst ab 2008. Der Einsatz dieser Methode in der Naturstoffsynthese hat bei Synthetikern seitdem immer mehr Interesse gefunden, und folgerichtig sind in der jüngeren Literatur zahlreiche Beispiele für Makrocyclisierungen dieses Typs beschrieben worden.

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Pronounced asymmetric amplification in the aldol condensation of Chan's diene promoted by a Ti(IV)/BINOL complex

Cited by 41 publications

References 31 publications

Nonlinear Effects in Asymmetric Catalysis

Nonlinear Effects in Asymmetric Catalysis

Catalytic, Enantioselective, Vinylogous Aldol Reactions

Die Prins‐Makrocyclisierung als effiziente Ringschluss‐Strategie in der Naturstoffsynthese

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