Total synthesis of (+)-obtusenyne

Uemura, Toshiyuki; Suzuki, Toshio; Onodera, Naohiro; Hagiwara, Hisahiro; Hoshi, Takashi

doi:10.1016/j.tetlet.2006.11.080

Cited by 16 publications

(8 citation statements)

References 20 publications

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“…Acetogenins containing two fused tetrahydrofuran rings can be differentiated into those with either a 2,6-dioxabicyclo[3. tetrahydrofuran ring derived from etherification between C-9 and C-12, thus forming a bicyclic ketal motif. Maneonenes (758)(759)(760)(761)(762)(763)(764)(765)(766) and isomaneonenes (767-769) contain three tetrahydrofuran rings and all feature a (E)-or (Z)-enyne terminus. However, their structures are unique among all reported C 15 acetogenins in that the carbon chain has cyclized back on itself to create a monocarbocyclic (through the formation of bond between C-6 and C-11) and a bicarbocyclic (through the formation of bonds between C-5 and C-13, as well as between C-6 and C-11) framework, respectively.…”

Section: Acetogeninsmentioning

confidence: 99%

“…Noteworthy is obtusenyne (892), the first nine-membered acetogenin to be isolated, which was obtained from two Mediterranean samples of Laurencia obtusa almost simultaneously by two different research groups [730,754]. Its first total synthesis was achieved in 1999 by the group of Murai [757], while three more synthetic protocols have also been reported [758][759][760]. Metabolite 897, for which the relative configurations of its asymmetric centers have not been assigned yet, was isolated from Laurencia implicata collected in Florence Bay, Magnetic Island, and is the sole representative of the ten-membered acetogenins [415].…”

Section: Acetogenins Containing An Eight-membered Cyclic Ether (Oxocamentioning

confidence: 99%

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The Laurencia Paradox: An Endless Source of Chemodiversity

Harizani

Iοannou

Roussis

2016

Progress in the Chemistry of Organic Natural Products

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Nature, the most prolific source of biological and chemical diversity, has provided mankind with treatments for health problems since ancient times and continues to be the most promising reservoir of bioactive chemicals for the development of modern drugs. In addition to the terrestrial organisms that still remain a promising source of new bioactive metabolites, the marine environment, covering approximately 70% of the Earth's surface and containing a largely unexplored biodiversity, offers an enormous resource for the discovery of novel compounds. According to the MarinLit database, more than 27,000 metabolites from marine macro- and microorganisms have been isolated to date providing material and key structures for the development of new products in the pharmaceutical, food, cosmeceutical, chemical, and agrochemical sectors. Algae, which thrive in the euphotic zone, were among the first marine organisms that were investigated as sources of food, nutritional supplements, soil fertilizers, and bioactive metabolites.Red algae of the genus Laurencia are accepted unanimously as one of the richest sources of new secondary metabolites. Their cosmopolitan distribution, along with the chemical variation influenced to a significant degree by environmental and genetic factors, have resulted in an endless parade of metabolites, often featuring multiple halogenation sites.The present contribution, covering the literature until August 2015, offers a comprehensive view of the chemical wealth and the taxonomic problems currently impeding chemical and biological investigations of the genus Laurencia. Since mollusks feeding on Laurencia are, in many cases, bioaccumulating, and utilize algal metabolites as chemical weaponry against natural enemies, metabolites of postulated dietary origin of sea hares that feed on Laurencia species are also included in the present review. Altogether, 1047 secondary metabolites, often featuring new carbocyclic skeletons, have been included.The chapter addresses: (1) the "Laurencia complex", the botanical description and the growth and population dynamics of the genus, as well as its chemical diversity and ecological relations; (2) the secondary metabolites, which are organized according to their chemical structures and are classified into sesquiterpenes, diterpenes, triterpenes, acetogenins, indoles, aromatic compounds, steroids, and miscellaneous compounds, as well as their sources of isolation which are depicted in tabulated form, and (3) the biological activity organized according to the biological target and the ecological functions of Laurencia metabolites.

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Section: Acetogeninsmentioning

confidence: 99%

Section: Acetogenins Containing An Eight-membered Cyclic Ether (Oxocamentioning

confidence: 99%

The Laurencia Paradox: An Endless Source of Chemodiversity

Harizani

Iοannou

Roussis

2016

Progress in the Chemistry of Organic Natural Products

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“…Notwithstanding, this drawback can be easily eliminated via replacement of water by chromophores, leading to more luminescent complexes. [32][33][34][35][36] The complex [Ln(fod) 3 (H 2 O) 2 ] (where fod ) 6,6,7,7,8,8, 8-heptafluoro-2,2-dimethyl-3,5-octadionate) has been widely applied as an NMR shift agent, [37][38][39][40][41] a catalyst in organic reactions, 42,43 and the subject of a handful of spectroscopic properties. [44][45][46][47][48][49] In previous studies, we have demonstrated that the replacement of the coordinated water molecules in the [Eu(fod) 3 (H 2 O) 2 ] by phen-N-O (1,10-phenanthroline N-oxide) or diphenyldipyridyl (4,4′-diphenyl-2,2′-dipyridyl) can cause significant improvements in the photoluminescent properties.…”

Section: Introductionmentioning

confidence: 99%

“…The complex [Ln(fod) 3 (H 2 O) 2 ] (where fod = 6,6,7,7,8,8, 8-heptafluoro-2,2-dimethyl-3,5-octadionate) has been widely applied as an NMR shift agent, − a catalyst in organic reactions, , and the subject of a handful of spectroscopic properties. − In previous studies, we have demonstrated that the replacement of the coordinated water molecules in the [Eu(fod) 3 (H 2 O) 2 ] by phen- N -O (1,10-phenanthroline N- oxide) or diphenyldipyridyl (4,4′-diphenyl-2,2′-dipyridyl) can cause significant improvements in the photoluminescent properties. , In addition, we have also investigated the effect on these properties of the inclusion of the complexes in glass and polymeric matrixes. − …”

Section: Introductionmentioning

confidence: 99%

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln³⁺−β-Diketonate Complexes

et al. 2010

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In this paper we report the synthesis of two new complexes, [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadionate and phen = 1,10-phenanthroline), and their complete characterization, including single-crystal X-ray diffraction, UV-vis spectroscopy, IR spectroscopy, and TGA. The complexes were studied in detail via both theoretical and experimental approaches to the photophysical properties. The [Eu(fod)(3)(phen)] complex crystallizes in the monoclinic space group P2(1)/c. The crystal structure of [Eu(fod)(3)(phen)] exhibits an offset pi-pi stacking interaction between the phenanthroline ligands of adjacent lanthanide complexes. The Eu(3+) cation is coordinated to three fod anionic ligands and to one phen. The symmetry around Eu(3+) is best described as a highly distorted square antiprism. The molar absorption coefficients of [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] revealed an improved ability to absorb light in comparison with the stand-alone phen and fod molecules. [Tb(fod)(3)(phen)] emits weak UV excitation, with this feature being explained by the triplet-(5)D(4) resonance, which contributes significantly to the nonradiative deactivation of Tb(3+), causing a short lifetime and low quantum yield. The intensity parameters (Omega(2), Omega(4), and Omega(6)) of [Eu(fod)(3)(phen)] were calculated for the X-ray and Sparkle/AM1 structures and compared with values obtained for [Eu(fod)(3)(H(2)O)(2)] and [Eu(fod)(3)(phen-N-O)] (phen-N-O = 1,10-phenanthroline N-oxide) samples. Intensity parameters were used to predict the radiative decay rate. The theoretical quantum efficiencies from the X-ray and Sparkle/AM1 structures are in good agreement with the experimental values, clearly attesting to the efficacy of the theoretical models.

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“…During the preparation of this manuscript, Suzuki and co-workers disclosed the fourth total synthesis of (+)-obtusenyne which involved the cyclisation of a linear hydroxy epoxide to form the core nine-membered ether directly. [14] Results and Discussion First generation approach to natural (+)-obtusenyne: Our retrosynthetic analysis of (+)-obtusenyne ((+)-1) is outlined in Scheme 1. We envisioned that the D…”

Section: Introductionmentioning

confidence: 99%

Synthesis of (+)‐Obtusenyne

Mak

Curtis

Payne

et al. 2008

Chemistry A European J

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An enantioselective synthesis of the halogenated medium-ring ether natural product (+)-obtusenyne is reported which uses the ring expansion of a seven-membered ketene acetal by means of a Claisen rearrangement to construct the core nine-membered oxygen heterocycle. The trans substituents across the ether linkage were established by using a transition-metal-catalyzed intramolecular hydrosilation reaction of an exo-cyclic enol ether. In addition, a formal synthesis of ent-obtusenyne from 2-deoxy-D-ribose is reported. A number of interesting points regarding the chemistry of medium-ring oxygen heterocycles are highlighted.

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Total synthesis of (+)-obtusenyne

Cited by 16 publications

References 20 publications

The Laurencia Paradox: An Endless Source of Chemodiversity

The Laurencia Paradox: An Endless Source of Chemodiversity

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln³⁺−β-Diketonate Complexes

Synthesis of (+)‐Obtusenyne

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Total synthesis of (+)-obtusenyne

Cited by 16 publications

References 20 publications

The Laurencia Paradox: An Endless Source of Chemodiversity

The Laurencia Paradox: An Endless Source of Chemodiversity

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln3+−β-Diketonate Complexes

Synthesis of (+)‐Obtusenyne

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Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln³⁺−β-Diketonate Complexes