De Novo Asymmetric Synthesis of Daumone via a Palladium-Catalyzed Glycosylation

“…By this approach, ODoherty and co-workers synthesized a number of complex oligosaccharides and glycoconjugates. [312] The key steps in their new synthetic route to the anthrax tetrasaccharide 245 involved palladium-catalyzed glycosylation reactions (Scheme 34, synthesis of intermediates 238, 240, and 243).…”

Section: Other Aspectsmentioning

confidence: 99%

New Principles for Glycoside‐Bond Formation

2009

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Increased understanding of the important roles that oligosaccharides and glycoconjugates play in biological processes has led to a demand for significant amounts of these materials for biological, medicinal, and pharmacological studies. Therefore, tremendous effort has been made to develop new procedures for the synthesis of glycosides, whereby the main focus is often the formation of the glycosidic bonds. Accordingly, quite a few review articles have been published over the past few years on glycoside synthesis; however, most are confined to either a specific type of glycoside or a specific strategy for glycoside synthesis. In this Review, new principles for the formation of glycoside bonds are discussed. Developments, mainly in the last ten years, that have led to significant advances in oligosaccharide and glycoconjugate synthesis have been compiled and are evaluated.

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“…Subsequent ring closure of 9 in the presence of I 2 afforded 4′-alloxyapigenin 10. Fluorescent analog 13 was prepared by applying olefin cross metathesis with Grubbs second-generation catalyst 11 to couple 10 to 12 (see ref 13). Complete synthetic details are provided within the Supporting Information.…”

Section: Daumone 1 Is Not the Only Natural Product That Can Induce Damentioning

confidence: 99%

“…Histological analyses in live C. elegans indicate that daumone (1), apigenin (13), and ascaroside 18 concentrate in the cuticle of the pharynx in worms prior to dauer entry and in adults. This localized material is then transited to amphid neurons as a signal for dauer entry.…”

Section: Blockage Of Neuronal Dye Uptakementioning

confidence: 99%

Metabolite Induction of Caenorhabditis elegans Dauer Larvae Arises via Transport in the Pharynx

et al. 2008

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Caenorhabditis elegans sense natural chemicals in their environment and use them as cues to regulate their development. This investigation probes the mechanism of sensory trafficking by evaluating the processing of fluorescent derivatives of natural products in C. elegans. Fluorescent analogs of daumone, an ascaroside, and apigenin were prepared by total synthesis and evaluated for their ability to induce entry into a nonaging dauer state. Fluorescent imaging detailed the uptake and localization of every labeled compound at each stage of the C. elegans life cycle.Comparative analyses against natural products that did not induce dauer indicated that dauertriggering natural products accumulated in the cuticle of the pharnyx. Subsequent transport of these molecules to amphid neurons signaled entry into the dauer state. These studies provide cogent evidence supporting the roles of the glycosylated fatty acid daumone and related ascarosides and the ubiquitous plant flavone apigenin as chemical cues regulating C. elegans development.In nature, the multifaceted lifecycle of nematodes typically involves passage through multiple host-guest relations (1). While genomic and proteomic experiments provide a blueprint of an organism, they do not provide a complete explanation of the molecular communication between organisms and their environment. Environmental signals often trigger responses that are far more complex than those elicited by a single genetic or proteomic event (2). Within recent years, the discovery and elucidation of small molecule signals that induce C. elegans into a dauer or resting state has opened a new avenue for understanding how environmental cues regulate development and aging (3). In this investigation, we focus attention on the physiological mechanisms by which C. elegans sense and process fluorescent analogs of natural products. Our studies compare endogenous and xenobiotic signals with an attempt to identify the molecular plasticity of the C. elegans HHMI Author Manuscript HHMI Author Manuscript HHMI Author ManuscriptC. elegans sense environmental signals in part through ciliated amphids at the tips of their heads and phasmids in their tails (4-6). Early tracking experiments established that fluorescent dyes such as fluorescein isothiocyanate (FITC) move from solution through the cilia at the top of their heads to sensory neurons within the amphid (7). While genetic approaches have uncovered aspects of the signal transduction pathways involved in this reception (8-10), the underlying mechanisms by which the chemical signals are transported and processed within C. elegans remain unresolved.Small molecules, including damone (1), trigger the entry of L1 larvae into a nonaging dauer state. Recently, the structure of 1 was determined by isolation from large scale extracts of C. elegans followed by a combination of NMR studies (11) and total syntheses (11,12). Using this molecule as a starting point, we investigated the transport of 1 and other non-dauerinducing natural products in C. elegans....

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De Novo Asymmetric Synthesis of Daumone via a Palladium-Catalyzed Glycosylation

Cited by 78 publications

References 22 publications

Transition metals in organic synthesis: Highlights for the year 2005

Transition metals in organic synthesis: Highlights for the year 2005

New Principles for Glycoside‐Bond Formation

Metabolite Induction of Caenorhabditis elegans Dauer Larvae Arises via Transport in the Pharynx

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