Stereoselective Aldol Reaction in Aqueous Solution Using Prolinamido-Glycosides as Water-Compatible Organocatalyst

Miura, Daisuke; Machinami, Tomoya

doi:10.4236/mrc.2015.41003

Cited by 8 publications

(4 citation statements)

References 28 publications

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“…The readily available parent aminoethanol catalyst 6e 41 and the aminophenol-based congener 6f 42 were consequently tested for their capacity to control the noncanonical polyketide cyclisation. Remarkably, an excellent selectivity and high yields were achieved with both catalysts, which effectively provided product 4a on a 100 μmol reaction scale (entries 8 and 9; 82% yield, 95:5 e.r.…”

Section: Resultsmentioning

confidence: 99%

Atroposelective synthesis of tetra-ortho-substituted biaryls by catalyst-controlled non-canonical polyketide cyclizations

et al. 2019

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The cyclisation of poly-β-carbonyl-substrates controlled by polyketide synthases intricately governs the biosynthesis of a wide range of aromatic polyketides. Analogous small-molecule catalysed processes would conceivably induce selective cyclisations of noncanonical polycarbonyl substrates to provide products distinct from natural polyketides. Herein, we report a secondary amine-catalysed twofold cyclisation of noncanonical hexacarbonyl substrates furnishing enantioenriched tetra-ortho-substituted binaphthalenes. The substrates were prepared by a fourfold ozonolysis of dicinnamyl biindenes and converted under catalyst-control with high atroposelectivity. Privileged catalysts and ligands were readily accessible from the binaphthalene products stemming from the noncanonical polyketide cyclisations.Poly-β-carbonyl chains, assembled by nonreducing polyketide synthases from acetate units, are biosynthetically diverged into a myriad of aromatic natural products. In particular their selective folding, aldol cyclisation and ensuing dehydration result in a broad range of skeletal variation, while tailoring steps further extend the diversity of the polyketide architecture (Fig. 1a). 1-3 Moreover, subsequent enzymatic dimerisations provide structurally markedly unique atropisomeric scaffolds, typically with control over the configuration of stereogenic axes. [4][5][6] Whereas the radical intermediates of dimerisation processes set the basis of biomimetic strategies, they also dictate the regioselectivity for ortho-and para-phenol couplings. 7,8 Taking into account that natural polyketides are restricted to a β-oxygenation pattern, [9][10][11] we anticipated that noncanonical 12 polyketide cyclisations governed by small-molecule catalysts would furnish valuable tetra-ortho-substituted atropisomeric biaryls distinct from dimerisation products. Considering the findings of stoichiometric biomimetic polyketide cyclisations, [13][14][15][16][17][18] we hence conceived a stereoselective polyketide cyclisation by means of catalytic substrate activation. More specifically, the controlled polyketide folding of substrate 2, characterised by a noncanonical oxygenation pattern (≠ β) obtained by an oxidative olefin cleavage of biindene 1, would directly give rise to atropisomeric binaphthalenes 4 by virtue of a twofold arene-forming aldol condensation (Fig. 1b, 2→4).

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Section: Resultsmentioning

confidence: 99%

Atroposelective synthesis of tetra-ortho-substituted biaryls by catalyst-controlled non-canonical polyketide cyclizations

et al. 2019

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“…However, the reaction of protected aldehydo‐D‐arabinose 23 and 20 in presence of 1 8b , gave the aldol adduct 24 and an undefined stereoisomer into 10 : 1 mixture (Scheme 15). [118] Machinami and co‐workers further extended the application of sugar prolin‐amide catalyst ( 18 a and 18 b ) as water‐compatible organocatalyst in stereoselective aqueous aldol reaction [119] . Furthermore, Peddinti et al .…”

Section: Carbohydrate Derived Prolinamide Pyrrolidines and Pyrrolidin...mentioning

confidence: 99%

Growing Impact of Carbohydrate‐Based Organocatalysts

et al. 2022

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Organocatalysis has emerged as one of the most progressive and prevailing field of organic synthesis to assist green chemistry. Constantly increasing demand of promising scaffolds to develop potent organocatalysts has impelled researchers to utilize the unique traits of carbohydrate moiety in this field. Biological significance of carbohydrates, as well as, their high natural abundance as chiral non‐racemic material, presence of multiple hydroxyl groups, several stereogenic centres, and easily modifiable structure make this moiety an appropriate skeleton to develop organocatalysts to enhance productivity and selectivity of a chemical transformation. 21st Century has witnessed the progress of carbohydrate moiety in development of organocatalysts from obscurity to eminence. This review encapsulates the importance of carbohydrate scaffolds in organocatalysis mainly dealing with the synthesis and applications carbohydrate‐derived organocatalyst in different common organic reactions with their significance and future purspectives.

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“…In a more recent article, Miura and Machinami described [ 143 ] other examples of aldol reaction catalysed by sugar prolinamides 271 and 272 ( Scheme 78 ). The reaction of isobutyraldehyde with acetone led to the ( R )-enantiomer (90%, ee = 89%) when performed in the presence of l -prolinamide 271 and the ( S )-enantiomer (89%, ee = 91%) when the d -prolinamide 272 was used.…”

Section: Sugar Prolinamidesmentioning

confidence: 99%

Synthesis and Applications of Carbohydrate-Based Organocatalysts

et al. 2021

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Organocatalysis is a very useful tool for the asymmetric synthesis of biologically or pharmacologically active compounds because it avoids the use of noxious metals, which are difficult to eliminate from the target products. Moreover, in many cases, the organocatalysed reactions can be performed in benign solvents and do not require anhydrous conditions. It is well-known that most of the above-mentioned reactions are promoted by a simple aminoacid, l-proline, or, to a lesser extent, by the more complex cinchona alkaloids. However, during the past three decades, other enantiopure natural compounds, the carbohydrates, have been employed as organocatalysts. In the present exhaustive review, the detailed preparation of all the sugar-based organocatalysts as well as their catalytic properties are described.

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Stereoselective Aldol Reaction in Aqueous Solution Using Prolinamido-Glycosides as Water-Compatible Organocatalyst

Cited by 8 publications

References 28 publications

Atroposelective synthesis of tetra-ortho-substituted biaryls by catalyst-controlled non-canonical polyketide cyclizations

Atroposelective synthesis of tetra-ortho-substituted biaryls by catalyst-controlled non-canonical polyketide cyclizations

Growing Impact of Carbohydrate‐Based Organocatalysts

Synthesis and Applications of Carbohydrate-Based Organocatalysts

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