Catalytic enantioselective Baylis-Hillman reactions. Correlation between pressure and enantiomeric excess

Markó, István E.; Giles, Paul R.; Hindley, Nigel J.

doi:10.1016/s0040-4020(96)01001-0

Cited by 147 publications

(47 citation statements)

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“…[94] Nevertheless, these reactions are notoriously slow, often requiring days to reach useful levels of conversion. Although physical methods, such as high pressure, [95] could address this problem, a chemical solution was lacking. Numerous mechanistic studies have attempted to explain the low catalytic efficiencies observed.…”

Section: Lewis Base Catalyzed Reactions Of Ketenesmentioning

confidence: 99%

Lewis Base Catalysis in Organic Synthesis

2008

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The legacy of Gilbert Newton Lewis (1875-1946) pervades the lexicon of chemical bonding and reactivity. The power of his concept of donor-acceptor bonding is evident in the eponymous foundations of electron-pair acceptors (Lewis acids) and donors (Lewis bases). Lewis recognized that acids are not restricted to those substances that contain hydrogen (Brønsted acids), and helped overthrow the "modern cult of the proton". His discovery ushered in the use of Lewis acids as reagents and catalysts for organic reactions. However, in recent years, the recognition that Lewis bases can also serve in this capacity has grown enormously. Most importantly, it has become increasingly apparent that the behavior of Lewis bases as agents for promoting chemical reactions is not merely as an electronic complement of the cognate Lewis acids: in fact Lewis bases are capable of enhancing both the electrophilic and nucleophilic character of molecules to which they are bound. This diversity of behavior leads to a remarkable versatility for the catalysis of reactions by Lewis bases.

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Section: Lewis Base Catalyzed Reactions Of Ketenesmentioning

confidence: 99%

Lewis Base Catalysis in Organic Synthesis

2008

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“…[94] Dennoch verlaufen diese Reaktionen langsam, sodass brauchbare Umsätze oft erst nach Tagen erreicht werden. Physikalische Methoden wie eine Druckerhöhung [95] konnten das Problem zwar lösen, eine chemische Methode fehlte aber. In zahlreichen mechanistischen Studien wurde versucht, die geringen katalytischen Wirksamkeiten zu erklären.…”

Section: Umfang Des Aufsatzesunclassified

Lewis‐Base‐Katalyse in der organischen Synthese

2008

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Das Erbe von Gilbert Newton Lewis (1875–1946) ist im Wörterbuch der chemischen Bindung und Reaktivität allgegenwärtig. Die Bedeutung seines Konzepts der Donor‐Akzeptor‐Bindung kommt in den eponymen Grundbegriffen für Elektronenpaarakzeptoren (Lewis‐Säuren) und ‐donoren (Lewis‐Basen) zum Ausdruck. Lewis erkannte, dass Säuren nicht automatisch Wasserstoff enthalten müssen (Brønsted‐Säuren) und trug so zum Sturz des “modernen Protonenkults” bei. Seine Entdeckung läutete zunächst die Entwicklung von Lewis‐Säuren als Reagentien und Katalysatoren für organische Reaktionen ein, in den letzten Jahren wurde aber offensichtlich, dass für diese Zwecke auch Lewis‐Basen eingesetzt werden können. Bezüglich der Beschleunigung chemischer Reaktionen ergänzen Lewis‐Basen die entsprechenden Lewis‐Säuren nicht nur elektronisch: Tatsächlich können Lewis‐Basen die Elektrophilie wie auch die Nucleophilie der Verbindungen verstärken, an die sie gebunden werden. Diese unterschiedliche Reaktivität resultiert in einer bemerkenswerten Vielfalt Lewis‐Base‐katalysierter Reaktionen.

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“…[1] As chiral b-hydroxy-a-methylene carbonyl compounds are useful intermediates in natural product synthesis, several enantioselective versions of this reaction involving chiral catalysts have been developed. For the BaylisHillman reaction of acrylate esters as electrophilic alkenes, [2,3] excellent enantioselectivities of up to 99% ee have been attained using b-isocupreidine (b-ICD) by Hatakeyama.[2] For the asymmetric Baylis-Hillman reaction of a,b-unsaturated ketones as electrophilic alkenes, however, although there were several precedents until recently, the enantioselectivity achieved has been moderate: Hirama [4] and Marko [5] developed chiral DABCO-type and quinidine-or cinchonine-based catalysts, respectively, which afforded modest enantioselectivities (47% ee, 45% ee) under high pressure conditions. The combination of a chiral calcium catalyst and tributylphosphine developed by Ikegami gave moderate enantioselectivity (56% ee) in the reaction of cyclopentenone.…”

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confidence: 99%

“…The generally accepted concept used in designing effective catalysts for the Baylis-Hillman reaction is that they should possess both a nucleophilic moiety and an acidic part, [2,5,7] or that two molecules, one acting as a nucleophile and the other as an acid, should be employed. [3b,6,8 -10] Marko [5] reported that a hydroxy group suitably positioned on an amine catalyst exerts a marked effect on rate acceleration as well as improving asymmetric induction by stabilizing the oxyanion intermediate through hydrogen bonding.…”

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The Chiral Diamine Mediated Asymmetric Baylis–Hillman Reaction

2004

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A chiral diamine, easily prepared from proline, is an effective, asymmetric organic catalyst for the Baylis-Hillman reaction of aldehydes and methyl vinyl ketone, affording adducts with enantioselectivities up to 75%.Keywords: asymmetric synthesis; Baylis-Hillman reaction; diamines; enones; Lewis base catalysts; organic catalysisThe Baylis-Hillman reaction is a synthetically useful method for the preparation of b-hydroxy-a-methylene carbonyl compounds in one-step from electrophilic alkenes and carbonyl compounds by using a tertiary amine or tertiary phosphine as an organic catalyst. [1] As chiral b-hydroxy-a-methylene carbonyl compounds are useful intermediates in natural product synthesis, several enantioselective versions of this reaction involving chiral catalysts have been developed. For the BaylisHillman reaction of acrylate esters as electrophilic alkenes, [2,3] excellent enantioselectivities of up to 99% ee have been attained using b-isocupreidine (b-ICD) by Hatakeyama.[2] For the asymmetric Baylis-Hillman reaction of a,b-unsaturated ketones as electrophilic alkenes, however, although there were several precedents until recently, the enantioselectivity achieved has been moderate: Hirama [4] and Marko [5] developed chiral DABCO-type and quinidine-or cinchonine-based catalysts, respectively, which afforded modest enantioselectivities (47% ee, 45% ee) under high pressure conditions. The combination of a chiral calcium catalyst and tributylphosphine developed by Ikegami gave moderate enantioselectivity (56% ee) in the reaction of cyclopentenone.[6] Good enantioselectivity (72% ee) has been attained using a chiral pyrrolizidine catalyst developed by Barrett.[7] The combination of a chiral sulfide with TiCl 4 promoted the Baylis-Hillman reaction of 3-phenylpropanal, affording the product in 74% ee, though an equimolar amount of the chiral sulfide had to be employed. [8] Just recently, Miller et al. have reported a dual catalyst composed of a nucleophile-loaded peptide and proline, which affords the product in up to 81% ee, [9] while Schaus reported that the combined use of chiral BINOL derivatives with PEt 3 realized enantioselectivities of up to 96% in the reaction of aldehydes and cyclohexenone.[10]The generally accepted concept used in designing effective catalysts for the Baylis-Hillman reaction is that they should possess both a nucleophilic moiety and an acidic part, [2,5,7] or that two molecules, one acting as a nucleophile and the other as an acid, should be employed. [3b,6,8 -10] Marko [5] reported that a hydroxy group suitably positioned on an amine catalyst exerts a marked effect on rate acceleration as well as improving asymmetric induction by stabilizing the oxyanion intermediate through hydrogen bonding.Chiral diamines have been developed by Mukaiyama et al. as effective ligands with various uses as asymmetric catalysts;[11] such compounds are also excellent organic catalysts for the kinetic optical resolution of alcohols as developed by Oriyama et al. [12] In our continuing investigatio...

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Catalytic enantioselective Baylis-Hillman reactions. Correlation between pressure and enantiomeric excess

Cited by 147 publications

References 31 publications

Lewis Base Catalysis in Organic Synthesis

Lewis Base Catalysis in Organic Synthesis

Lewis‐Base‐Katalyse in der organischen Synthese

The Chiral Diamine Mediated Asymmetric Baylis–Hillman Reaction

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