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Search for "structure elucidation" in Full Text gives 123 result(s) in Beilstein Journal of Organic Chemistry.
Isolation and characterisation of irinans, androstane-type withanolides from Physalis peruviana L.
Beilstein J. Org. Chem. 2019, 15, 2003–2012, doi:10.3762/bjoc.15.196
- lower than those of 4ß-hydroxywithanolide E. Our work establishes androwithanolides as a new subclass of withanolides. Keywords: androstanes; Physalis peruviana; steroids; structure elucidation; withanolides; Introduction Traditional medicine has long been a source of inspiration for modern drug
Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions
Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145
- and structure elucidation are both in progress and will aid the development of an, at least, kilolab-scale procedure for standardised quality products. Experimental The details of the reactions are described in Supporting Information File 1. All reagents and organic solvents were used without further
New terpenoids from the fermentation broth of the edible mushroom Cyclocybe aegerita
Beilstein J. Org. Chem. 2019, 15, 1000–1007, doi:10.3762/bjoc.15.98
- clusters. Keywords: bioinformatics; gene cluster analysis; natural products; secondary metabolites; structure elucidation; terpenes; Introduction The basidiomycete Agrocybe aegerita (synonym: A. cylindracea) was traditionally accommodated in the genus Agrocybe (family Bolbitiaceae) until a recent
Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry
Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66
- extra synthetic steps that make the atom economy of this approach very low and the entire synthetic procedure time consuming. Structure elucidation of difunctionalized CDs is a challenging task, irrespective of the strategy used. In the direct difunctionalization approach, the disulfonyl-capped CD has
- scalable, amenable to chromatographic separation and reproducible difunctionalization methods. Moreover, the direct NMR spectroscopic analysis would provide structure elucidation without any reference material, time-consuming chemical conversions or enzymatic degradation. Hetero-difunctionalized CDs are
New sesquiterpenoids from the South China Sea soft corals Clavularia viridis and Lemnalia flava
Beilstein J. Org. Chem. 2019, 15, 695–702, doi:10.3762/bjoc.15.64
- investigation of two title animals led to the isolation of four new halogenated laurane-type sesquiterpenoids 1–4, one new aromadendrane-type sesquiterpenoid 6) together with three related known compounds 5, 7 and 8 (Figure 1). Herein, the isolation, structure elucidation and bioactivity evaluation of these
Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines
Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41
- intermediates 2 and 3 in hand, we proceeded with the synthesis and structure elucidation of the designed structures G and H (Figure 1) which are represented by compounds 7–11 in Scheme 1. Firstly, we prepared a regioisomeric compound 5 by repeating the previously elaborated sequence of double CuAAC reaction (2
Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum
Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277
- , and therefore it is mandatory for unambiguous structure elucidation to compare analytes that fall into this class to all the possible isomers. A similar problem can apply to the structural assignment of compounds with multiple stereocentres based on GC–MS data, because the various possible
- patterns are sufficiently different for a confident structural assignment. Also biosynthetic considerations can help in the structure elucidation, because some aromatic substitution patterns are in line with a polyketide biosynthesis mechanism, while other substitution patterns may be difficult to
- (10), trimethylpyrazine (11) and 2-ethyl-3,6-dimethylpyrazine (12) were also observed. These compounds were previously reported from the actinobacterium Corynebacterium glutamicum in which pyrazines are biosynthetically derived from acetoin and its higher homologs [24]. For unambiguous structure
N-Acylated amino acid methyl esters from marine Roseobacter group bacteria
Beilstein J. Org. Chem. 2018, 14, 2964–2973, doi:10.3762/bjoc.14.276
- them have been characterized so far [14][15][16][17][18]. Such signalling compounds as well as many other unknown metabolites often occur in small amounts, which renders trace detecting methods like GC/MS a suitable approach for their detection and structure elucidation, provided their polarity falls
Protein–protein interactions in bacteria: a promising and challenging avenue towards the discovery of new antibiotics
Beilstein J. Org. Chem. 2018, 14, 2881–2896, doi:10.3762/bjoc.14.267
- identification requires detailed structure elucidation, which in the end makes the design of an effective PPI modulator both difficult and challenging [19][20][21][22]. PPI modulation can be achieved through two opposite but complementary approaches: stabilization or inhibition (Figure 1). Although so far the
Herpetopanone, a diterpene from Herpetosiphon aurantiacus discovered by isotope labeling
Beilstein J. Org. Chem. 2017, 13, 2458–2465, doi:10.3762/bjoc.13.242
- pathway. After large-scale fermentation of H. aurantiacus 114-95T, the putative diterpene was isolated in sufficient quantity to enable NMR-based structure elucidation. The compound, for which the name herpetopanone is proposed, features a rare octahydro-1H-indenyl skeleton. Herpetopanone bears
- . Although the elemental composition does not necessarily exclude a polyketide origin, it perfectly matches a diterpene comprising four intact isoprene units. To obtain sufficient material for structure elucidation, the fermentation of H. aurantiacus 114-95T was repeated on a 50 L scale in VNY medium
- assignment of several other protons and the readout of their coupling constants was challenging due to severe signal overlapping. A TOCSY spectrum suggested that, with the exception of four methyl groups (CH3-1, CH3-3, CH3-13, CH3-20), all protons were part of the same spin system. Structure elucidation
Enzymatic separation of epimeric 4-C-hydroxymethylated furanosugars: Synthesis of bicyclic nucleosides
Beilstein J. Org. Chem. 2017, 13, 2078–2086, doi:10.3762/bjoc.13.205
- concentrated under reduced pressure to afford a colourless oil. The two products formed in the reaction had different polarity and were easily separated by column chromatography over silica gel in quantitative yields. The structure elucidation of the two products revealed that Novozyme®-435 exhibited exclusive
18-Hydroxydolabella-3,7-diene synthase – a diterpene synthase from Chitinophaga pinensis
Beilstein J. Org. Chem. 2017, 13, 1770–1780, doi:10.3762/bjoc.13.171
- , revealing that the expression of one and the same terpene synthase in different heterologous hosts may yield different terpene products. Keywords: biosynthesis; Chitinophaga pinensis; Nicotiana benthamiana; structure elucidation; terpenes; Introduction Terpene synthases convert a handful of simple linear
The chemistry and biology of mycolactones
Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159
A new member of the fusaricidin family – structure elucidation and synthesis of fusaricidin E
Beilstein J. Org. Chem. 2017, 13, 1430–1438, doi:10.3762/bjoc.13.140
- BASF SE, 67056 Ludwigshafen, Germany 10.3762/bjoc.13.140 Abstract Two hitherto unknown fusaricidins were obtained from fermentation broths of three Paenibacillus strains. After structure elucidation based on tandem mass spectrometry and NMR spectroscopy, fusaricidin E was synthesized to confirm the
- structure and the suggested stereochemistry. The synthesis was based on a new strategy which includes an efficient access to the 15-guanidino-3-hydroxypentadecanoyl (GHPD) side chain from erucamide. Keywords: cyclodepsipeptides; fusaricidins; lipopeptides; structure elucidation; total synthesis
- (Figure 1). Thus, an assumed stereoisomer (containing D-allo-Ile) of the new fusaricidin member was synthesized based on analogy to known members of the series and compared to the natural product [8]. Results and Discussion Isolation and structure elucidation The Paenibacillus strain was cultivated on
New tricks of well-known aminoazoles in isocyanide-based multicomponent reactions and antibacterial activity of the compounds synthesized
Beilstein J. Org. Chem. 2017, 13, 1050–1063, doi:10.3762/bjoc.13.104
- -amino-5-methylisoxazole (7) according to the elaborated procedures (Table 1, methods A or B) as well as under other conditions were not successful. Structure elucidation The purity and structures of the heterocycles obtained were established by means of mass spectrometry (including HRMS), NMR
Cycloheximide congeners produced by Streptomyces sp. SC0581 and photoinduced interconversion between (E)- and (Z)-2,3-dehydroanhydrocycloheximides
Beilstein J. Org. Chem. 2017, 13, 1039–1049, doi:10.3762/bjoc.13.103
- . Results and Discussion Structure elucidation The molecular formula of compound 1 was established as C15H21NO4 based on the HRESI(+)-MS ion at m/z 302.1357 [M + Na]+ (calcd 302.1363). Its 1H and 13C NMR spectral data (Table 1), in combination with the HSQC spectrum, indicated the presence of a conjugated
- findings suggested that these cycloheximide derivatives possibly exert the antifungal and cytotoxic activities via a similar mode of action. Conclusion Three new (1–3) and three known (4–6) cycloheximide congeners were obtained from the cultures of Streptomyces sp. SC0581. The structure elucidation of the
Novel β-cyclodextrin–eosin conjugates
Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52
- standard nitration conditions to obtain the desired dye eosin B (4) (Figure 1). The NMR spectra showing the structure elucidation of the free dyes eosin Y (2) and eosin B (4) are shown in Supporting Information File 1, Figures S3–S7 and Figures S15–S19, respectively. Synthesis of eosin Y–β-CD and eosin B–β
Secondary metabolome and its defensive role in the aeolidoidean Phyllodesmium longicirrum, (Gastropoda, Heterobranchia, Nudibranchia)
Beilstein J. Org. Chem. 2017, 13, 502–519, doi:10.3762/bjoc.13.50
- feeding deterrence under laboratory conditions at concentration levels below natural abundance in the sea slug bodies. Herein we report on the secondary metabolome of a single specimen of P. longicirrum, including the structure elucidation of the new metabolites 1, 5, 9, 14 and 15, and show the fish
- tentative. It can, however be stated that the P. longicirrum specimen investigated in this study either belongs to a different chemotype or has different food preference than the one investigated by Coll and co-workers [13]. Detailed chemical investigation of P. longicirrum including structure elucidation
Polyketide stereocontrol: a study in chemical biology
Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39
- ][32][33][34][35][36][37], in combination with structure elucidation at high resolution of AT5 from the DEBS PKS, which was solved in the presence of acetate (Figure 7) [38]. For example, extender unit-specific ATs contain positively charged residues in the active site (R667 and H745, DEBS AT5
- stereochemistry by site-directed mutagenesis awaits identification of further stereochemical determinants in ER active sites. Bioinformatics-guided structure elucidation The strong correlations between certain sequence motifs present in PKS domains and the stereochemistry of the resulting polyketide chains has
- ‘Caffrey’ motifs are present (for example, the LDD motif indicative of B-type KRs, with the second D being most diagnostic, particularly for trans-AT PKSs) and therefore these predictions can be an important complement to full structure elucidation. On the other hand, some KRs possess sequence features of
Supramolecular frameworks based on [60]fullerene hexakisadducts
Beilstein J. Org. Chem. 2017, 13, 1–9, doi:10.3762/bjoc.13.1
- . Keywords: fullerenes; hexakisadducts; hydrogen bonding; porous materials; structure elucidation; Introduction The utilization of confined nanospace in rigid frameworks [1], which are derived from small molecular precursors under dynamic conditions, has emerged as a novel design paradigm for functional
O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside
Beilstein J. Org. Chem. 2016, 12, 2828–2833, doi:10.3762/bjoc.12.282
- was available for molecular replacement and the protein contains only one methionine and no cysteine residues, which is insufficient to consider incorporation of selenomethionine in the protein for the structure elucidation. Its carbohydrate-binding specificity was determined and a preference for O
Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris
Beilstein J. Org. Chem. 2016, 12, 2731–2738, doi:10.3762/bjoc.12.269
- several isomers, helpful for the structure elucidation of natural compounds, e.g., in chemical ecology or fragrance research. The mass spectral fragmentation of macrolides differs markedly from that of open-chain esters, because initial bond cleavage often does not lead to the release of an uncharged
Enduracididine, a rare amino acid component of peptide antibiotics: Natural products and synthesis
Beilstein J. Org. Chem. 2016, 12, 2325–2342, doi:10.3762/bjoc.12.226
- B Enduracidin A (7) and B (8) were first isolated from Streptomyces fungicidicus B 5477 from a soil sample collected in Nishinomiya, Japan (Figure 2) [1]. Detailed reports of the isolation procedures, in vivo and in vitro antimicrobial activity, physical properties and structure elucidation have
New furoisocoumarins and isocoumarins from the mangrove endophytic fungus Aspergillus sp. 085242
Beilstein J. Org. Chem. 2016, 12, 2077–2085, doi:10.3762/bjoc.12.196
- known compounds (3, 4, 7–9) (Figure 1). Details of the isolation, structure elucidation, and biological activity of these compounds are reported herein. Results and Discussion The mangrove endophytic fungus Aspergillus sp. 085242 was cultured on solid rice medium with saline water for four weeks. The
Mechanistic investigations on six bacterial terpene cyclases
Beilstein J. Org. Chem. 2016, 12, 1839–1850, doi:10.3762/bjoc.12.173
- terpene cyclases were characterised by one- and two-dimensional NMR spectroscopic methods, allowing for a full structure elucidation. The absolute configurations of four terpenes were determined based on their optical rotary powers. Incubation experiments with 13C-labelled isotopomers of FPP in buffers
- containing water or deuterium oxide allowed for detailed insights into the cyclisation mechanisms of the bacterial terpene cyclases. Keywords: absolute configuration; biosynthesis; enzyme mechanisms; structure elucidation; terpenes; Introduction Terpenes are structurally fascinating natural products with
- cyclases, purification and full structure elucidation of their products by NMR and determination of optical rotary powers. Furthermore, the enzyme mechanisms of the investigated terpene cyclases were studied by isotopic labelling experiments [34] similar to recently reported investigations on other
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