Computation-Assisted Structural Elucidation of Epoxyroussoeone and Epoxyroussoedione Isolated from <i>Roussoella japanensis</i> KT1651

Honmura, Yuna; Takekawa, Hiroto; Tanaka, Kazuaki; Maeda, Hayato; Nehira, Tatsuo; Hehre, Warren J.; Hashimoto, Minoru

doi:10.1021/np500924n

Cited by 17 publications

(21 citation statements)

References 18 publications

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“…It should be noted that there have been publications where initially a set of possible structures is suggested based on manual NMR data analysis, and then prediction of 13 C chemical shifts is performed using QM methods to select the best structure. [90][91][92][93] For instance, the work [94] that was devoted to the revision of the structure of aquatolide by Lodewyk et al performed DFT calculations of 13 C chemical shifts for 60 proposed structures to select the most probable one. The inefficiency of this approach has been convincingly demonstrated [95] -in this case, ACD/SE produced three probable structures (see structures 2-4 in Section 4.2.2), and then the DFT calculations confirmed the validity of structure 2.…”

Section: Nmr Chemical Shift Prediction: Synergy Between Empirical and Dft Approachesmentioning

confidence: 99%

Computer Assisted Structure Elucidation (CASE): Current and future perspectives

Elyashberg¹,

Argyropoulos²

2020

Magnetic Reson in Chemistry

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The first efforts for the development of methods for Computer-Assisted Structure Elucidation (CASE) were published more than 50 years ago. CASE expert systems based on one-dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) data have matured considerably by now. The structures of a great number of complex natural products have been elucidated and/or revised using such programs. In this article, we discuss the most likely directions in which CASE will evolve. We act on the premise that a synergistic interaction exists between CASE, new NMR experiments, and methods of computational chemistry, which are continuously being improved. The new developments in NMR experiments (long-range correlation experiments, pure-shift methods, coupling constants measurement and prediction, residual dipolar couplings [RDCs]), and residual chemical shift anisotropies [RCSAs], evolution of density functional theory (DFT), and machine learning algorithms will have an influence on CASE systems and vice versa. This is true also for new techniques for chemical analysis (Atomic Force Microscopy [AFM], "crystalline sponge" X-ray analysis, and micro-Electron Diffraction [micro-ED]), which will be used in combination with expert systems. We foresee that CASE will be utilized widely and become a routine tool for NMR spectroscopists and analysts in academic and industrial laboratories. We believe that the "golden age" of CASE is still in the future.

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Section: Nmr Chemical Shift Prediction: Synergy Between Empirical and Dft Approachesmentioning

confidence: 99%

Computer Assisted Structure Elucidation (CASE): Current and future perspectives

Elyashberg¹,

Argyropoulos²

2020

Magnetic Reson in Chemistry

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“…We observed the 3 J coupling in alkyne-containing spiro-oxiranes (3 a-h, 5, 10, 16, 17, 18) was typically 7.7 Hz and the 3 J coupling of aryl-containing products (2 a-x, 4, 8, 9, 11-15, 21-23) was typically 11.7 Hz. When terminal alkyne 16 underwent a click reaction, the 3 J coupling changed from 7.4 Hz (starting material, ( 16)) to 10.6 Hz (product,(22,23)). We suspected that the small alkyne substituent would face minimal steric interactions when axial, whereas the larger aryl substituents would prefer to be equatorial to avoid unfavourable 1,3-diaxial interactions.…”

Section: Angewandte Chemiementioning

confidence: 99%

“…The reaction was then repeated using the achiral [Rh(cod)Cl] 2 catalyst and the alkynylated spirooxirane 10 was obtained in modest yield and the stereochemistry was assigned using residual dipolar coupling analysis. [23] These products were readily transformed into a wide array of functionalized products (Scheme 2). A diverse range of nucleophiles including bromide (11), thiol (12), piperazine (13), cyanide (14), and azide ( 15) can be used to open the epoxide moiety giving enantioenriched 1,2-difunctionalized tertiary alcohols.…”

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confidence: 99%

Enantioselective Synthesis of Spiro‐oxiranes: An Asymmetric Addition/Aldol/Spirocyclization Domino Cascade

2021

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Enantioenriched spiro-oxiranes bearing three contiguous stereocenters were synthesized using a rhodium-catalyzed asymmetric addition/aldol/spirocyclization sequence. Starting from a linear substrate, the cascade enabled the formation of a spirocyclic framework in a single step. sp 2 -and sp-hybridized carbon nucleophiles were found to be competent initiators for this cascade, giving arylated or alkynylated products, respectively. Derivatization studies demonstrated the synthetic versatility of both the epoxide and the alkyne moieties of the products. DFT calculations were used to reconcile spectroscopic discrepancies observed between the solution-and solid-state structures of the products.

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“…Follow up investigations on two additional species, R. japanensis KT1651 and Roussoella sp. DLM33, yielded two highly oxidized xanthone derivatives [ 9 ] and a dichlorinated polyketide, respectively [ 10 ]. During our exploration of new Dothideomycetes in Thailand, a Roussoella sp.…”

Section: Introductionmentioning

confidence: 99%

Biofilm Inhibitory Abscisic Acid Derivatives from the Plant-Associated Dothideomycete Fungus, Roussoella sp.

et al. 2018

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Roussoella species are well recorded from both monocotyledons and dicotyledons. As part of a research program to discover biologically active compounds from plant-associated Dothideomycetes in Thailand, the strain Roussoella sp. (MFLUCC 17-2059), which represents an undescribed species, was isolated from Clematis subumbellata Kurz, fermented in yeast-malt medium and explored for its secondary metabolite production. Bioassay-guided fractionation of the crude extract yielded the new abscisic acid derivative, roussoellenic acid (1), along with pestabacillin B (2), a related congener, and the cyclodipeptide, cyclo(S-Pro-S-Ile) (3). The structure of 1 was determined by 2D NMR spectroscopy and HR-ESIMS data analysis. Compounds 1 and 2 showed inhibitory activity on biofilm formation by Staphylococcus aureus. The biofilm formation of S. aureus was reduced to 34% at 16 µg/mL by roussoellenic acid (1), while pestabacillin B (2) only showed 36% inhibition at 256 µg/mL. In addition, compound 1 also had weak cytotoxic effects on L929 murine fibroblasts and human KB3-1 cancer cells.

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Computation-Assisted Structural Elucidation of Epoxyroussoeone and Epoxyroussoedione Isolated from Roussoella japanensis KT1651

Cited by 17 publications

References 18 publications

Computer Assisted Structure Elucidation (CASE): Current and future perspectives

Computer Assisted Structure Elucidation (CASE): Current and future perspectives

Enantioselective Synthesis of Spiro‐oxiranes: An Asymmetric Addition/Aldol/Spirocyclization Domino Cascade

Biofilm Inhibitory Abscisic Acid Derivatives from the Plant-Associated Dothideomycete Fungus, Roussoella sp.

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