Rapid, room-temperature acylative kinetic resolution of sec-alcohols using atropisomeric 4-aminopyridine/triphenylphosphine catalysis

Spivey, Alan C.; Arseniyadis, Stellios; Fekner, Tomasz; Maddaford, Adrian; Leese, David

doi:10.1016/j.tet.2005.08.124

Cited by 43 publications

(13 citation statements)

References 24 publications

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“…Für das Auftreten dieser aktivierten Spezies sprechen IR-und UV-spektroskopische sowie kristallographische Untersuchungen. Die planare Struktur des Ions er- [58] und -achsen [59] zeigt ähnliche Selektivität wie die ursprünglichen chiralen DMAP-Derivate. Auch andere Klassen von Stickstoffheterocyclen, wie das von Birman und Mitarbeitern entwickelte 9, waren hoch selektiv.…”

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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Section: Umfang Des Aufsatzesunclassified

Lewis‐Base‐Katalyse in der organischen Synthese

2008

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“…Variations of 7 (Ar=Ph, R′=Et) by using R=Me instead of R=H resulted in a lower enantioselectivity for the same reaction 54. An improvement of catalyst 7 was achieved by varying the R′ group (R′= n ‐butyl showed the best performance; Table 1, entry 4);55 the variation of the aryl moiety also led to better selectivities56 (Table 1, entry 6). Catalyst (−)‐ 7 was also tested in the kinetic resolution of monobenzoylated meso ‐(cyclo)alkane‐1,2‐diols such as 48 (Table 2, entry 5) and in the desymmetrization of meso ‐(cyclo)alkane‐1,2‐diols such as 51 (Table 3, entry 4) 57.…”

Section: Enantioselective Acyl Transfer Using 4‐aminopyridines As mentioning

confidence: 99%

Organocatalytic Enantioselective Acyl Transfer onto Racemic as well as meso Alcohols, Amines, and Thiols

2011

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Acyl transfer is at the heart of functional-group transfers utilized both in nature and in the chemical laboratory. Acylations are part of the natural assembly machinery for the generation of complex molecules and for energy transport in biological systems. The recognition of covalent acyl-enzyme intermediates led to both mechanistic studies as well as the development of biomimetic approaches. Consequently, chemists first used the tools of nature in the form of enzymes and naturally occurring alkaloids as catalysts, before eventually developing a large variety of synthetic small molecules for selective acyl transfer. In contrast to nature, chemists utilize acylation reactions as a practical way for stereoselection and functional-group protection. Indeed, the number of studies concerning acyl transfer has significantly increased over the last 15 years. This Review examines and highlights these recent developments with the focus as given in the title.

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“…The same transformation run at -40 8C proceeds with a selectivity factor s of 54. [55][56][57][58][59][60][61] The configurational stability of the synthesized biaryl 4-(dimethylamino)pyridine derivatives has been estimated, and the configurationally stable biaryl 4-(dimethylamino)pyridine derivatives have been evaluated as asymmetric acyl-transfer catalysts. A characteristic feature of the transformation is the complete consumption of the anhydride employed.…”

Section: Bmentioning

confidence: 99%

Chiral DMAP-Type Catalysts for Acyl-Transfer Reactions

2012

Asymmetric Organocatalysis 1

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Reactivity of DMAP-Type Catalysts4-(Dimethylamino)pyridine (1, DMAP) (Scheme 1) is a valuable and powerful organocatalyst which catalyzes acylation of a wide variety of alcohols. [1][2][3][4][5][6][7][8] In these reactions, 4-(dimethylamino)pyridine works as a nucleophilic catalyst which mediates acyl-transfer reactions from an acyl donor to the substrate via acylpyridinium reactive intermediate 3 (Scheme 2). In 1967, it was found that 4-(dimethylamino)pyridine accelerates the benzoylation of 3-chloroaniline faster than pyridine does by a factor of ca. 10 4 . [9] Independently, the superior activity of 4-(dimethylamino)pyridine as an acylation catalyst was revealed in 1969. [10] It has also been reported that 4-(pyrrolidin-1-yl)pyridine (2, PPY) (Scheme 1) has higher catalytic activity in acylation reactions than 4-(dimethylamino)pyridine. [11] These landmark findings have opened up the chemistry of DMAP-type catalysis. DMAP-catalyzed acyl-transfer reactions have been utilized for O-acylation of alcohol substrates, Nacylation of amine substrates, and C-acylation of enolates and their equivalents. In particular, asymmetric acyl-transfer reactions catalyzed by chiral DMAP-type catalysts have attracted great attention. A wide variety of chiral DMAP-type and PPY-type catalysts have been developed in the last 15 years and the research field on chiral DMAP-catalysis is still rapidly expanding. [12][13][14][15][16][17][18][19][20][21][22][23] Scheme 1 Structure of 4-(Dimethylamino)pyridine and 4-(Pyrrolidin-1yl)pyridine N NMe 2 1 DMAP N N 2 PPYThe currently accepted mechanism of DMAP-catalyzed acylation of alcohols is shown in Scheme 2. Acylpyridinium ion 3 is formed by nucleophilic attack of 4-(dimethylamino)pyridine (1) on an acyl donor. Under the pre-equilibrium between acylpyridinium ion 3 and 4-(dimethylamino)pyridine/acyl donor, acylpyridinium ion 3 undergoes nucleophilic attack by alcohol 4 to give ester 6 and protonated (deactivated) catalyst 7 via transition state 5. Regeneration of the active catalyst 1 usually requires an auxiliary base such as triethylamine. More recently, an efficient acylation process has been reported employing a small amount (0.05-2 mol%) of 4-(dimethylamino)pyridine in the absence of auxiliary bases. [24] 497 for references see p 544This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

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Rapid, room-temperature acylative kinetic resolution of sec-alcohols using atropisomeric 4-aminopyridine/triphenylphosphine catalysis

Cited by 43 publications

References 24 publications

Lewis‐Base‐Katalyse in der organischen Synthese

Lewis‐Base‐Katalyse in der organischen Synthese

Organocatalytic Enantioselective Acyl Transfer onto Racemic as well as meso Alcohols, Amines, and Thiols

Chiral DMAP-Type Catalysts for Acyl-Transfer Reactions

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