Highly enantioselective organocatalysis of the Hajos–Parrish–Eder–Sauer–Wiechert reaction by the β-amino acid cispentacin

Davies, Stephen G.; Sheppard, Ruth L.; Smith, Andrew D.; Thomson, James E.

doi:10.1039/b506780b

Cited by 100 publications

(26 citation statements)

References 27 publications

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“…When (1R,2S)-cis-pentacin (302, 30 mol%) was used as catalyst for the cyclization of 2a, the aldol intermediate ent-3 was obtained in an excellent 90% ee. Furthermore, treatment with p-toluenesulfonic acid led to compound ent-4a in 94% overall yield [356]. In the reaction with ketone 2b (n = 2, R = Me; Table 3.1) better results (93% yield and 86% ee) than those obtained with proline were obtained.…”

Section: Intramolecular Reactionsmentioning

confidence: 80%

Organocatalyzed Aldol Reactions

Guillena¹

2013

Modern Methods in Stereoselective Aldol Reactions

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The use of catalytic enantioselective methods to perform an aldol reaction provides a direct entry for the synthesis of chiral compounds and is probably the most attractive way to achieve this goal with high control of the chemo-, regio-, diastereo-, and enantioselectivity. The application of biochemical methods based on enzyme aldolases or antibodies, which are discussed in other chapters, avoid the use of preformed enolates or their equivalents for enhancing the global atom efficiency of the process [1] for which the narrow substrate scope is a major drawback. The discovery of methodologies to carry out the enantioselective direct aldol reaction [2] has eluded the production of stoichiometric by-products increasing the substrate scope. This task could be accomplished by using small molecules as catalysts, such as metal complexes (which are covered along this book) and organic molecules, also known as organocatalysts [3]. The growth of this last research area and the direct aldol reaction are closely linked [4], with the report on the use of (S)-proline as catalyst for the intermolecular aldol [5] definitely being the push for the development of the organocatalytic methods as a competitive methodology for the synthesis of chiral compounds.In a strict sense, an organocatalyzed reaction is a process in which all the involved reagents and catalysis are purely organic compounds of low-molecular weight, excluding boron-and silicon-containing derivatives. However, in some cases, the presence of a silyl group only plays a steric role and therefore can also be considered as an organocatalyzed process. Also, if the organocatalyst involved in a reaction is immobilized in a polymer, a dendrimer, or even an inorganic material that serves only as a support to facilitate its recovery [6], it could still be considered as an organocatalyst, although those types of derivatives have been scarcely used in the natural product synthesis and therefore will be excluded from this chapter. Therefore, a comprehensive overview of the direct aldol reaction [7], emphasizing the reactivity, scope, selectivity, and limitations of the methodology and giving several examples of their application to the synthesis of biologically active compounds, is discussed in this chapter.

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Section: Intramolecular Reactionsmentioning

confidence: 80%

Organocatalyzed Aldol Reactions

Guillena¹

2013

Modern Methods in Stereoselective Aldol Reactions

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“…When (1R,2S)-cispentacin 46 (30 mol%) was used as a catalyst for 6-endo aldol reactions of triketone 35, the corresponding bicyclic diketone 37 was obtained in excellent yield with enantioselectivity. 33 The absolute configuration of product 37 is (R), whereas (S)-isomer 37 is obtained by use of (S)-proline 6. Limbach then reported a study of different β-amino acids as aldol catalysts: β 3 -homoproline 47 affords diketone 37 in excellent yields but with low enantioselectivities; however, the use of β-amino acids 48-51 bearing aliphatic side chains results in modest yields but with good enantioselectivities.…”

Section: Cyclization Of Ketone Nucleophiles With Ketone Electrophilesmentioning

confidence: 99%

2.07 The Aldol Reaction: Organocatalysis Approach

Mase

Hayashi²

2014

Comprehensive Organic Synthesis II

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“…6 Recently, extensions of this chemistry have been published and much more selective organocatalysts have been developed. [68][69][70][71] The combination of proline-catalyzed aldol reactions with other methods of forming carbon-carbon bonds leads to a versatile strategy for multi-component condensation: with Knoevenagel, 72 with self-aldol, 73 with aldehyde α-amination, 74 and with Knoevenagel-reduction. 75…”

Section: Aldol-related Reactionsmentioning

confidence: 99%

Organocatalytic Asymmetric Synthesis Using Proline and Related Molecules. Part 2.

Kotsuki¹,

Ikishima²,

Okuyama³

2008

HETEROCYCLES

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-Organocatalytic asymmetric synthesis has been extensively studied and several important procedures for preparing optically active organic compounds have been developed. Research in this area has progressed rapidly in the last ten years. This review addresses the most significant advances in asymmetric synthesis using proline and related chiral organocatalysts mainly focusing on aldol reactions from the viewpoint of synthetic interests. This includes (1) proline-catalyzed aldol reactions, (2) proline-related chiral catalysts, and (3) other types of amino acid catalysts.

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Highly enantioselective organocatalysis of the Hajos–Parrish–Eder–Sauer–Wiechert reaction by the β-amino acid cispentacin

Abstract: The beta-amino acid cispentacin promotes the Hajos-Parrish-Eder-Sauer-Wiechert reaction with levels of enantioselectivity comparable to or higher than proline.

Cited by 100 publications

References 27 publications

Organocatalyzed Aldol Reactions

Organocatalyzed Aldol Reactions

2.07 The Aldol Reaction: Organocatalysis Approach

Organocatalytic Asymmetric Synthesis Using Proline and Related Molecules. Part 2.

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