Highly Diastereo‐ and Enantioselective Direct Aldol Reactions in Water

Hayashi, Yujiro; Sumiya, Tatsunobu; Takahashi, J.; Gotoh, Hiroaki; Urushima, Tatsuya; Shoji, Mitsuru

doi:10.1002/anie.200502488

Cited by 482 publications

(184 citation statements)

References 33 publications

(13 reference statements)

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“…The proline-catalyzed direct aldol reaction in water does not work. [5] Recently, the organocatalyzed direct aldol reaction in water has been indipendently reported by Hayashi [6] and Barbas III. [5] Previously, the aqueous aldol reaction between acetone and 4-nitrobenzaldehyde catalyzed by a nicotine metabolite was reported.…”

Section: Introductionmentioning

confidence: 96%

New Simple Hydrophobic Proline Derivatives as Highly Active and Stereoselective Catalysts for the Direct Asymmetric Aldol Reaction in Aqueous Medium

et al. 2008

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New 4-substituted acyloxyproline derivatives with different hydrophobic properties of the acyl group were easily synthesized and used as catalysts in the direct asymmetric aldol reaction between cyclic ketones (cyclohexanone and cyclopentanone) and several substituted benzaldehydes. Reactions were carried out using water, this being the best reaction medium examined. Screening of these catalysts showed that compounds bearing the most hydrophobic acyl chains [4-phenylbutanoate and 4-(pyren-1-yl)butanoate] provided better results. The latter catalysts were successfully used in only 2 mol% at room temperature without additives to give aldol products in excellent stereoselectivities. These results demonstrate that derivatization of the proline moiety with the proper simple hydrophobic substituent in the 4-position can furnish highly active and stereoselective catalysts without the need of additional chiral backbones in the molecule. Finally, an explanation of the observed stereoselectivities in the presence of water is provided.

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Section: Introductionmentioning

confidence: 96%

New Simple Hydrophobic Proline Derivatives as Highly Active and Stereoselective Catalysts for the Direct Asymmetric Aldol Reaction in Aqueous Medium

et al. 2008

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“…1c remained intact without iodine under conditions A and B, signifying the role of iodine. The role of acidity of the hydroxyl group and the C-2 hydrogen atom of C-2 halogenated tertiary alcohols 1f and 1g in I 2 -catalyzed transformation was examined (Table 1, entries [11][12][13][14].…”

Section: Resultsmentioning

confidence: 99%

“…9 It has been documented that water can remarkably affect the course of the reaction, [10][11][12] including enantioselectivity. [13][14][15] Water has become a reaction solvent of immense importance for the selectivity/reactivity studies of nucleophiles and electrophiles, [16][17][18] where carbocation intermediates play an important role. [19][20][21] Mixtures of water with organic solvents have been employed to determine the geometry of the transition states, 22 with the hydrophobic effect attracting attention in studies of organic reactions in the presence of water.…”

Section: Introductionmentioning

confidence: 99%

Iodine-catalyzed Transformation of Aryl-substituted Alcohols Under Solvent-free and Highly Concentrated Reaction Conditions

Jereb

Vrazic²

2017

ACSi

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Iodine-catalyzed transformations of alcohols under solvent-free reaction conditions (SFRC) and under highly concentrated reaction conditions (HCRC) in the presence of various solvents were studied in order to gain insight into the behavior of the reaction intermediates under these conditions. Dimerization, dehydration and substitution were the three types of transformations observed with benzylic alcohols. Dimerization and substitution reactions were predominant in the case of primary-and secondary alcohols, whereas dehydration prevailed in the case of tertiary alcohols. The relative reactivity of substituted 1-phenylethanols in I 2 -catalyzed dimerization under SFRC provided a good Hammett plot ρ + = −2.8 (r 2 = 0.98), suggesting the presence of electron-deficient intermediates with a certain degree of developed charge in the rate-determining step.

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“…97 Interestingly, Hayashi and coworkers discovered that 4-decanoyloxyproline 4 efficiently catalyzed the cross-aldol reaction of aldehydes in aqueous media (yield up to 92%, dr up to >20 : 1, ee up to 99%) (Scheme 33). 100,103 Although the precise mechanism is unclear, it is possible that the surfactant-like nature of catalyst 4 brought the acceptor and donor molecules together on the water surface. …”

Section: Oxyproline Catalystsmentioning

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 Diastereo‐ and Enantioselective Direct Aldol Reactions in Water

Cited by 482 publications

References 33 publications

New Simple Hydrophobic Proline Derivatives as Highly Active and Stereoselective Catalysts for the Direct Asymmetric Aldol Reaction in Aqueous Medium

New Simple Hydrophobic Proline Derivatives as Highly Active and Stereoselective Catalysts for the Direct Asymmetric Aldol Reaction in Aqueous Medium

Iodine-catalyzed Transformation of Aryl-substituted Alcohols Under Solvent-free and Highly Concentrated Reaction Conditions

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

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