Synthesis of Cardiac Glycoside Analogs by Catalyst-Controlled, Regioselective Glycosylation of Digitoxin

Beale, Thomas M.; Taylor, Mark S.

doi:10.1021/ol4003042

Cited by 71 publications

(50 citation statements)

References 69 publications

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“…[1] As illustrated in the work of Kawabata, [2] Miller, [3] and Taylor, [4] the site-selective modification of carbohydrates and other natural polyols provides direct access to compounds that otherwise would require numerous steps to prepare. Taking advantage of the native reducing ability of alcohols, we have developed a family of redox-triggered carbonyl additions wherein hydrogen transfer from alcohols to π-unsaturated reactants produces electrophile-nucleophile pairs en route to products of formal alcohol C-H functionalization via carbonyl addition.…”

Section: Introductionmentioning

confidence: 99%

Catalyst‐Directed Diastereo‐ and Site‐Selectivity in Successive Nucleophilic and Electrophilic Allylations of Chiral 1,3‐Diols: Protecting‐Group‐Free Synthesis of Substituted Pyrans

Shin

Wang

Krische

2014

Chemistry A European J

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Section: Introductionmentioning

confidence: 99%

Catalyst‐Directed Diastereo‐ and Site‐Selectivity in Successive Nucleophilic and Electrophilic Allylations of Chiral 1,3‐Diols: Protecting‐Group‐Free Synthesis of Substituted Pyrans

Shin

Wang

Krische

2014

Chemistry A European J

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“…161 One such complex molecular target is digitoxin ( 86 ), which contains a trisaccharide appended to the C3-position of a steroid core. Reagents must choose between five hydroxyl groups to glycosylate.…”

Section: Group Transfer To Hydroxyl Groupsmentioning

confidence: 99%

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

2017

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The application of small molecules as catalysts for the diversification of natural product scaffolds is reviewed. Specifically, principles that relate to the selectivity challenges intrinsic to complex molecular scaffolds are summarized. The synthesis of analogs of natural products by this approach is then described as a quintessential “late-stage functionalization” exercise wherein natural products serve as the lead scaffolds. Given the historical application of enzymatic catalysts to the site-selective alteration of complex molecules, the focus of this review is on the recent studies of non-enzymatic catalysts. Reactions involving hydroxyl group derivatization with a variety of electrophilic reagents are discussed. C–H bond functionalizations that lead to oxidations, aminations, and halogenations are also presented. Several examples of site-selective olefin functionalizations and C–C bond formations are also included. Numerous classes of natural products have been subjected to these studies of site-selective alteration including polyketides, glycopeptides, terpenoids, macrolides, alkaloids, carbohydrates and others. What emerges is a platform for chemical remodeling of naturally occurring scaffolds that targets virtually all known chemical functionalities and microenvironments. However, challenges for the design of very broad classes of catalysts, with even broader selectivity demands (e.g., stereoselectivity, functional group selectivity, and site-selectivity) persist. Yet, a significant spectrum of powerful, catalytic alterations of complex natural products now exists such that expansion of scope seems inevitable. Several instances of biological activity assays of remodeled natural product derivatives are also presented. These reports may foreshadow further interdisciplinary impacts for catalytic remodeling of natural products, including contributions to SAR development, mode of action studies, and eventually medicinal chemistry.

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“…Unlike most other glycosylation reactions this method does not require the strict use of anhydrous conditions; combined with the low toxicity and easy removal of the catalyst, it offers a valuable addition to oligosaccharide synthesis strategies. This methodology was later successfully applied to the regioselective glycosylation of the cardiac glycoside natural product digitoxin . More recently, in 2014, the Taylor group extended their use of the organoboron catalyst to the preparation of 2‐deoxy‐ and 2,6‐dideoxyglycosides .…”

Section: Organoboron Catalyzed Glycosylationsmentioning

confidence: 99%

Recent Advances in Organocatalytic Glycosylations

Williams

Galan

2017

Eur J Org Chem

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms MICROREVIEW Recent Advances in Organocatalytic GlycosylationsRyan Williams [a] and M. Carmen Galan* [a] Dedication ((optional))Abstract: Carbohydrates play a pivotal role in biological systems and present an opportunity to develop potent carbohydrate derived therapeutics and diagnostic tools for the treatment and detection of disease. To better comprehend the biological functions of carbohydrates, access to pure and structurally defined oligosaccharides is needed. Oligosaccharides are commonly synthesized by chemical means, however, despite progress in glycosylation chemistry, the efficient and stereoselective formation of glycosidic bonds by mild, non-toxic and low-cost methods remains a challenge. Organocatalysis is an exciting field that utilizes small organic molecules to effect chemical transformation where traditionally transition metal catalysis would be required. This microreview presents recent advances in the application of organocatalysis to carbohydrate chemistry and in particular to the stereoselective synthesis of oligosaccharides.

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Synthesis of Cardiac Glycoside Analogs by Catalyst-Controlled, Regioselective Glycosylation of Digitoxin

Cited by 71 publications

References 69 publications

Catalyst‐Directed Diastereo‐ and Site‐Selectivity in Successive Nucleophilic and Electrophilic Allylations of Chiral 1,3‐Diols: Protecting‐Group‐Free Synthesis of Substituted Pyrans

Catalyst‐Directed Diastereo‐ and Site‐Selectivity in Successive Nucleophilic and Electrophilic Allylations of Chiral 1,3‐Diols: Protecting‐Group‐Free Synthesis of Substituted Pyrans

Applications of Nonenzymatic Catalysts to the Alteration of Natural Products

Recent Advances in Organocatalytic Glycosylations

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