Sonogashira Couplings of Halo‐ and Epoxy‐Halo‐<i>exo</i>‐Glycals: Concise Entry to Carbohydrate‐Derived Enynes

Gómez, Ana M.; Barrio, Alicia; Pedregosa, Ana; Uriel, Clara; Valverde, Serafı́n; López, J. Cristóbal

doi:10.1002/ejoc.201000170

Cited by 18 publications

(6 citation statements)

References 126 publications

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“…We had previously shown that structurally related vinyl halides could be engaged in a variety of palladium-catalysed reactions, [32] including Suzuki cross-couplings, [33,34] leading to monosubstituted exo-glycals. We thus carried out Suzuki couplings between the vinyl halides 28-30 and the boronic acids 42-44 to give the allylic amines 41, and our results are displayed in Table 2.…”

Section: Reactions At the Alkenyl Halide Component -Generation Of Furmentioning

confidence: 99%

1‐exo‐Alkylidene‐2,3‐anhydrofuranoses: Valuable Synthons in the Preparation of Furanose‐Based Templates

et al. 2010

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Highly functionalized 1‐exo‐alkylidene‐2,3‐anhydro‐, and 1′‐halo‐1‐exo‐alkylidene‐2,3‐anhydrofuranoses can be prepared in four or five steps, respectively, from D‐mannose. These compounds feature a variety of functionalities, including a double bond, an oxirane, an allylic oxirane and (in the case of the 1′‐halo derivative) an alkenyl halide. The reactivity of each functionality in these derivatives has been explored, and the usefulness of these substrates has been demonstrated with the preparation of furanose‐based carbohydrate templates with up to four sites of molecular diversity.

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Section: Reactions At the Alkenyl Halide Component -Generation Of Furmentioning

confidence: 99%

1‐exo‐Alkylidene‐2,3‐anhydrofuranoses: Valuable Synthons in the Preparation of Furanose‐Based Templates

et al. 2010

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“…The main methods to synthesize exo-glycals are Wittig-like olefinations, [16] the Ramberg-Bäcklund rearrangement, [17] the modified Julia olefination, [18] and the stepwise addition-elimination of sugar lactones. [19] Recently,d ifferent functionalizations, [20] such as the Sonogashira, [21] Suzuki, [22] and Stille cross-coupling reactions, [23] have allowed the preparation of tetrasubtituted exo-glycals.H owever, to our knowledge, there is no general method to synthesize tetrasubstituted exo-glycals bearingt wo electron-withdrawing groups.I nf act, the methodology developed by Lin, [19] which consists of an ucleophilic addition of al ithiated methyl-phosphonate to asugar lactone, does not yield the desired addition product when al ithiated phosphonate bearing an electronwithdrawing group is used (Figure 2, PathA). This lack of reactivity is likely due to the poor nucleophilicity of the phosphonate.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Unprecedented Sulfonylated Phosphono‐exo‐Glycals Designed as Inhibitors of the Three Mycobacterial Galactofuranose Processing Enzymes

Frédéric

Tikad

et al. 2016

Chemistry A European J

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This study reports a new methodology to synthesize exo-glycals bearing both a sulfone and a phosphonate. This synthetic strategy provides a way to generate exo-glycals displaying two electron-withdrawing groups and was applied to eight different carbohydrates from the furanose and pyranose series. The Z/E configurations of these tetrasubstituted enol ethers could be ascertained using NMR spectroscopic techniques. Deprotection of an exo-glycal followed by an UMP (uridine monophosphate) coupling generated two new UDP (uridine diphosphate)-galactofuranose analogues. These two Z/E isomers were evaluated as inhibitors of UGM, GlfT1, and GlfT2, the three mycobacterial galactofuranose processing enzymes. Molecule 46-(E) is the first characterized inhibitor of GlfT1 reported to date and was also found to efficiently inhibit UGM in a reversible manner. Interestingly, GlfT2 showed a better affinity for the (Z) isomer. The three enzymes studied in the present work are not only interesting because, mechanistically, they are still the topic of intense investigations, but also because they constitute very important targets for the development of novel antimycobacterial agents.

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“…The exocyclic β‐halo enol ether 19 was envisioned to be a useful starting point for the total synthesis of pachastrissamine17, 18 ( 22 ; Scheme ) through cross‐coupling reactions. For this purpose, the obtained bromo‐methylene 19 was subjected to Sonogashira conditions with tridec‐1‐yne 19. The reaction occurred readily in acetonitrile20 and gave the desired coupling product 20 in 64 % yield (73 % based on recovery of starting material) with complete retention of configuration.…”

Section: Methodsmentioning

confidence: 99%

Silver‐Mediated exo‐Selective Tandem Desilylative Bromination/Oxycyclization of Silyl‐Protected Alkynes: Synthesis of 2‐Bromomethylene‐Tetrahydrofuran

Lee

Lim

Hwang

et al. 2011

Chemistry An Asian Journal

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Dedicated to Professor Eun Lee on the occasion of his retirement and 65th birthdayTandem reactions are one-pot multi-step processes and are thus among the most useful synthetic methods. [1] Recently, the use of transition metals in tandem reactions has received considerable attention and has revolutionized the synthetic strategies in organic chemistry. [2] Among the transition metal-based tandem reactions, the processes that involve heterocyclization reactions of unsaturated substrates are of particular interest, [3,4] as they provide a direct method for the construction of synthetically and biologically valuable heterocycles.The intramolecular heterocyclization of g or d-hydroxyalkynes promises to be a convenient way to access the functionalized tetrahydrofurans and pyrans, which are common motifs in a variety of natural products. This cyclization can be driven by transition metal catalysts, and the regioselectivity of these reactions varies depending on the metal and the conditions employed. [5] Among the metals thus far reported for these reactions, silver and gold have been demonstrated to be the most effective and selective for the formation of exo-dig products. [6,7] These metals can promote heterocyclization of both internal and terminal alkynes. Even halogenated and silylated alkynes can be converted into the corresponding exo-dig products using these metals.

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Sonogashira Couplings of Halo‐ and Epoxy‐Halo‐exo‐Glycals: Concise Entry to Carbohydrate‐Derived Enynes

Cited by 18 publications

References 126 publications

1‐exo‐Alkylidene‐2,3‐anhydrofuranoses: Valuable Synthons in the Preparation of Furanose‐Based Templates

1‐exo‐Alkylidene‐2,3‐anhydrofuranoses: Valuable Synthons in the Preparation of Furanose‐Based Templates

Synthesis of Unprecedented Sulfonylated Phosphono‐exo‐Glycals Designed as Inhibitors of the Three Mycobacterial Galactofuranose Processing Enzymes

Silver‐Mediated exo‐Selective Tandem Desilylative Bromination/Oxycyclization of Silyl‐Protected Alkynes: Synthesis of 2‐Bromomethylene‐Tetrahydrofuran

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