Catalytic Enantioselective Synthesis of Flavanones and Chromanones.

Biddle, Margaret; Lin, Michael; Scheidt, Karl A.

doi:10.1002/chin.200735137

Cited by 7 publications

(13 citation statements)

References 2 publications

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“…Chiral thioureas derived from quinine/quinidine scaffolds have been adapted as synthetic mimetics of CHI enantioselective functionality. 39,40 The human gut bacterium, Eubacterium ramulus, which evolved CHI activity from an unrelated protein fold, reverses the reaction for flavonoid catabolism. 41,42 The bacterial CHI is similar to plant CHIs in its selectivity for (2S)flavanones; however, for the bacterial CHI, an active site histidine facilitates a general acid/base catalysis.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Bifunctional Substrate Activation via an Arginine Residue Drives Catalysis in Chalcone Isomerases

et al. 2019

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Chalcone isomerases are plant enzymes that perform enantioselective oxa-Michael cyclizations of 2¢-hydroxychalcones into flavanones. An X-ray crystal structure of an enzyme-product complex and molecular dynamics simulations reveal an enzyme mechanism wherein the guanidinium ion of a conserved arginine positions the nucleophilic phenoxide and activates the electrophilic enone for cyclization through Brønsted and Lewis acid interactions. The reaction terminates by asymmetric protonation of the carbanion intermediate syn to the guanidinium. Interestingly, bifunctional guanidine-and urea-based chemical reagents, increasingly used for asymmetric organocatalytic applications, are synthetic counterparts to this natural system. Comparative protein crystal structures and molecular dynamics simulations further demonstrate how two active site water molecules coordinate a hydrogen bond network that enables expanded substrate reactivity for 6¢-deoxychalcones in more recently evolved type-2 chalcone isomerases. ASSOCIATED CONTENT Supporting InformationDetailed experimental protocols and computational protocols, crystallographic data, supporting data figures, NMR spectra, HPLC chromatograms, MD simulation data, and CHI-1/CHI-2 phylogenetic analyses are included.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Bifunctional Substrate Activation via an Arginine Residue Drives Catalysis in Chalcone Isomerases

et al. 2019

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“…Biddle et al recently reported the discovery of a bifunctional quinine-derived thiourea catalyst that effectively regulates the chemical outcome and produces either a lefthanded molecule or a right-handed molecule, not a one-to-one mixture of both. This catalyst was used in flavanones and chromanones synthesis and high yields were reported with excellent enantioselectivity, in addition to the advantages of further modification capability [20]. Apart from chemical synthesis, different polyphenols biosynthesis approaches with each offers advantages and disadvantages are available, for example plant extract, plant cell cultures, and recombinant microororganisms.…”

Section: Biosynthesis Methodsmentioning

confidence: 99%

Bioavailability and Recent Advances in the Bioactivity of Flavonoid and Stilbene Compounds

Koffas¹

2010

COC

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Polyphenols such as flavonoids and stilbenes are abundant in our daily diet, and their roles in the protection and prevention of various diseases are substantial. However, the bioavailability varies among polyphenols and the actual compounds acting on the designated tissues are often not the native molecules consumed in the diet. Hereby, we review the bioavailabilty of the main classes of stilbenes and flavonoids, namely flavanones, flavones, isoflavones, flavanols, flavonols and anthocyanins, emphasizing on their absorption, distribution, metabolism and excretion (ADME). The bioavailability summary can be useful for future experimental design, especially the emphasis on the bioactivity on targeted tissues and organs. In addition, we review the bioefficacy of the polyphenols, emphasizing recent advances on health benefits both in vivo and in vitro. Other issues of importance, such as structure, food source and synthesis methods, are also considered.

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“…319 Other catalysts have been used to perform the intramolecular oxa-Michael cyclization, and we discuss now the reaction with chiral 9-(benzyloxy)cinchonidine thiourea (3R,8S,9R)-CXLVII. 320 The reaction was first optimized on tert-butyl 3-(2-hydroxyphenyl)-3-oxo-2-benzylidenepropanoate (E)-657, which afforded tert-butyl 3,4-dihydro-4-oxo-2-phenyl-2H-chromene-3-carboxylate [(2R,3S)-658] through an oxa-Michael attack on the β-Re face and the sequential syn addition. Then the reaction was run under the conditions that led to the decarboxylation product (R)-659 (Scheme 271).…”

Section: Formation Of the O(1)−c(2) Bondmentioning

confidence: 99%

“…Then the reaction was run under the conditions that led to the decarboxylation product (R)-659 (Scheme 271). 320 Considering the structure of the cinchona fragment of the catalyst and the stereochemical outcome, the reader will certainly be surprised by the analogies of this reaction with the reaction described in Scheme 270 from (Z)-652 to (8S,9S)-653.…”

Section: Formation Of the O(1)−c(2) Bondmentioning

confidence: 99%

Forty Years after “Heterodiene Syntheses with α,β-Unsaturated Carbonyl Compounds”: Enantioselective Syntheses of 3,4-Dihydropyran Derivatives

2018

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This review is focused on the enantioselective synthesis of 3,4-dihydropyran derivatives, whose importance as chiral building blocks in the synthesis of bioactive molecules and natural products is well established. The review analyzes the different synthetic strategies by grouping them as a function of the atom numbers of the reagents involved. Starting from the classical [4 + 2] and [2 + 4] approaches, the [3 + 3], [5 + 1], and [6] strategies have been sequentially analyzed, and for each of them, the asymmetry induced by both chiral metal complexes and different kinds of organocatalysts has been examined. More than 400 papers have been reviewed, whose results have been described in the highest synthetic manner, in the attempt to emphasize the mechanism of the chirality transfer from the chiral messengers to the reaction products. This analysis allows the great flexibility of the diverse catalytic systems, the complementary of the results obtained from the different reaction pathways, and the very high level of control of the achievable molecular complexity to be evidenced.

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Catalytic Enantioselective Synthesis of Flavanones and Chromanones.

Cited by 7 publications

References 2 publications

Bifunctional Substrate Activation via an Arginine Residue Drives Catalysis in Chalcone Isomerases

Bifunctional Substrate Activation via an Arginine Residue Drives Catalysis in Chalcone Isomerases

Bioavailability and Recent Advances in the Bioactivity of Flavonoid and Stilbene Compounds

Forty Years after “Heterodiene Syntheses with α,β-Unsaturated Carbonyl Compounds”: Enantioselective Syntheses of 3,4-Dihydropyran Derivatives

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