Two antibacterial and PPARα/γ-agonistic unsaturated keto fatty acids from a coral-associated actinomycete of the genus Micrococcus

• Amit Raj Sharma,
• Enjuro Harunari,
• Naoya Oku,
• Nobuyasu Matsuura,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 297–304, doi:10.3762/bjoc.16.29

• Shimadzu UV-1800 and a Perkin-Elmer Spectrum 100 spectrophotometer, respectively. NMR spectra were obtained on a Bruker AVANCE 500 spectrometer in CDCl3 using the signals of the residual solvent (δH 7.26) and (δC 77.0) as internal standards. HRESIMS-TOF was recorded on a Bruker micrOTOF focus

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• organic chemists towards reaching targets selectively from readily available starting materials using low cost, nontoxic reagents and solvents while maintaining high atom and step economy and minimizing waste production with respect to safety standards, electroorganic chemistry (EOC) stands out as a

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

• Heather J. Lacey,
• Cameron L. M. Gilchrist,
• Andrew Crombie,
• John A. Kalaitzis,
• Daniel Vuong,
• Peter J. Rutledge,
• Peter Turner,
• John I. Pitt,
• Ernest Lacey,
• Yit-Heng Chooi and
• Andrew M. Piggott

Beilstein J. Org. Chem. 2019, 15, 2631–2643, doi:10.3762/bjoc.15.256

• library (>7,100 standards) also failed to provide a single known secondary metabolite, further suggesting the strain was a hitherto unaccounted species of Aspergillus. A. nanangensis was cultivated separately on jasmine rice and pearl barley for 21 days, which resulted in confluent and thick mycelial

Isolation and biosynthesis of an unsaturated fatty acid with unusual methylation pattern from a coral-associated bacterium Microbulbifer sp.

• Amit Raj Sharma,
• Enjuro Harunari,
• Tao Zhou,
• Agus Trianto and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2019, 15, 2327–2332, doi:10.3762/bjoc.15.225

• was recorded on a Shimadzu UV-1800 spectrophotometer. The IR spectrum was measured on a Perkin-Elmer Spectrum 100. NMR spectra were obtained on a Bruker AVANCE 500 spectrometer in CDCl3 using the signals of the residual solvent proton (δH 7.26) and carbon (δH 77.0) as internal standards. HR-ESI-TOFMS

Analysis of sesquiterpene hydrocarbons in grape berry exocarp (Vitis vinifera L.) using in vivo-labeling and comprehensive two-dimensional gas chromatography–mass spectrometry (GC×GC–MS)

• Philipp P. Könen and
• Matthias Wüst

Beilstein J. Org. Chem. 2019, 15, 1945–1961, doi:10.3762/bjoc.15.190

• ) coupled to a time-of-flight mass spectrometer (TOF–MS) after headspace-solid phase microextraction (HS-SPME). The identification of structurally complex natural compounds, such as sesquiterpenes from fruits and vegetables, is often reported as “tentative”, as authentic standards are not commercially

• advantages of multidimensional gas chromatography with those of in vivo labeling. In vivo labeling makes it possible to identify compounds for which authentic standards are not commercially available, which applies to the majority of compounds found in plant foods [18]. We performed feeding experiments on

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• fractions; such compounds are too complex for analysis at a molecular level, so it is important to synthesize analytical standards for their study. In this context, Schulze et al. optimized a multicomponent cyclocondensation reaction [50][51] between 5α-cholestan-3-one (43), aromatic aldehydes and 2

Mechanochemical amorphization of chitin: impact of apparatus material on performance and contamination

• Thomas Di Nardo and
• Audrey Moores

Beilstein J. Org. Chem. 2019, 15, 1217–1225, doi:10.3762/bjoc.15.119

• iCap 6500 Duo Series spectrometer. The samples were digested in aqua regia (5 mL) for 2 hours at 90 °C. The samples were then diluted to total volume of 50 mL with DI water and run against standards of the elements of interest. Kinetic energy calculation Kinetic energy of the ball determined by using

Mechanistic investigations on multiproduct β-himachalene synthase from Cryptosporangium arvum

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2019, 15, 1008–1019, doi:10.3762/bjoc.15.99

• comparison with commercially available standards (Figures S6–S9, Supporting Information File 1). The non-enzymatic degradation of GPP as a background reaction to 15 resulted in a substantial loss of stereoinformation for this compound (7% ee). Also the cyclised products 10, 11 and 13 where not obtained in

Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

• Sora Park and
• Jeung Gon Kim

Beilstein J. Org. Chem. 2019, 15, 963–970, doi:10.3762/bjoc.15.93

• HPLC grade, Fisher) at 40 °C at 1.0 mL/min and calibrated using 14 monodisperse polystyrene standards (Alfa Aesar). The temperature was recorded using a Fluke VT04 Visual IR thermometer. Synthesis of trimethylene carbonate. 1,3-Propanediol (4.72 mL, 0.657 mol) and ethyl chloroformate (12.5 mL, 0.131

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• -permeation chromatography on the instrument Agilent Technologies 1260 Infinity with a refractive index detector, GPC/SEC – styrogel column, length 300 mm, internal diameter 7.5 mm, eluent (CHCl3) rate 1 mL/s, calibration according to the polystyrene standards known molecular weight. Thermal analysis was

Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• fascinating small and bioactive amide. Results and Discussion We first synthesized 1 and 1-methylnematophin (3) as standards to confirm preliminary results. We then initiated the synthesis of derivatives 2, and 4–12. Briefly, the appropriate α-keto carboxylic acid was coupled to the respective amine. Amide

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• were monitored through UV light. Flash chromatography was carried out on silica gel 300–400 mesh. 1H and 13C NMR spectra were recorded in CDCl3 at 500 and 126 MHz, respectively, using the solvents as internal standards. High-resolution mass spectra were taken on Waters Synapt MS. The peak patterns are

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases

• Antonella Petri,
• Valeria Colonna and
• Oreste Piccolo

Beilstein J. Org. Chem. 2019, 15, 60–66, doi:10.3762/bjoc.15.6

• °C. The eluent was H2O/CH3CN/DEA 70:30:0.1. Authentic standards were analyzed before analysis of the reaction mixtures. The enantiomeric excesses were determined after derivatization. An aliquot (50 mg) of the crude sample and 100 mg K2CO3 were added to a 15 mL volumetric flask and dissolved in 1 mL

Selective ring-opening metathesis polymerization (ROMP) of cyclobutenes. Unsymmetrical ladderphane containing polycyclobutene and polynorbornene strands

• Yuan-Zhen Ke,
• Shou-Ling Huang,
• Guoqiao Lai and
• Tien-Yau Luh

Beilstein J. Org. Chem. 2019, 15, 44–51, doi:10.3762/bjoc.15.4

• recorded on a Varian 400 Unity Plus NMR spectrometer using CDCl3 as solvent at ambient temperature. Chemical shifts were expressed in parts per million using residual solvent protons as internal standards (1H: chloroform: 7.26 ppm). Gel permeation chromatography (GPC) was performed on a Waters GPC

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• was accomplished with H,H-COSY, HMBC or HSQC spectra. Deuterated solvents chloroform-d1 and DMSO-d6 were obtained from Deutero GmbH and the remaining non-deuterated solvent signals were used as internal standards as references for the 1H shifts and 13C shifts which are all reported on the δ [ppm

New standards for collecting and fitting steady state kinetic data

• Kenneth A. Johnson

Beilstein J. Org. Chem. 2019, 15, 16–29, doi:10.3762/bjoc.15.2

• rate to fall off as substrate is consumed but account for the deviation from linearity by fitting the data using computer simulation. Product inhibition can also be resolved if it contributes significantly to the data [11]. Standards for data collection When it is possible, data should be collected at

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum

• Jan Rinkel,
• Alexander Babczyk,
• Tao Wang,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277

• diastereomers usually also produce very similar mass spectra [16], a phenomenon that is also reported for E and Z stereoisomers and can lead to wrong structural assignments, if no authentic standards are used for comparison [17]. We have recently reported on two chlorinated aromatic compounds from an endophytic

• elucidation commercially available standards of 9–11 were used, while a synthesis of 12 was performed in our earlier study [24]. Furthermore, a group of monoterpenes and the sesquiterpene alcohol pogostol (19) that was previously reported from other fungi [29][30] were observed. Monoterpenes were comprised of

• (Scheme 1). Comparison of the GC retention index of the natural product (I = 1225) to the retention indices of all six standards narrowed the possible structures down to those of 2,4,5-trimethylanisole (I = 1225) and 2,3,5-trimethylanisole (I = 1227), while all other isomers could be ruled out. The final

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

• Iveta Tichá,
• Gábor Benkovics,
• Milo Malanga and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2018, 14, 2829–2837, doi:10.3762/bjoc.14.261

• ] (reaction 4) were used as standards. The regioisomeric pattern was thus concluded: the AD regioisomer eluted first, the AC regioisomer second and the AB regioisomer last. Synthesis and large-scale separation of heterobifunctionalized α-CDs After elucidating the homofunctionalized regioisomeric pattern, we

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• recent years, attempts to raise public awareness on antimicrobial resistance (AMR) and the large threat that it poses towards modern health standards have been made [1]. It is an alarming notion that at an increasing rate of available treatment options proves ineffective in eradicating bacterial

Synthesis of a leopolic acid-inspired tetramic acid with antimicrobial activity against multidrug-resistant bacteria

• Luce Mattio,
• Loana Musso,
• Leonardo Scaglioni,
• Andrea Pinto,
• Piera Anna Martino and
• Sabrina Dallavalle

Beilstein J. Org. Chem. 2018, 14, 2482–2487, doi:10.3762/bjoc.14.224

• Laboratory Standards Institute guidelines [30]. All the strains were treated with a panel of antimicrobial molecules belonging to five pharmacological categories: amoxicillin + clavulanic acid, cephalexin, cefovecin, clindamycin, doxycycline, enrofloxacin and marbofloxacin. Only for S. pseudintermedius

A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines

• Katherine E. Jolley,
• Michael R. Chapman and
• A. John Blacker

Beilstein J. Org. Chem. 2018, 14, 2220–2228, doi:10.3762/bjoc.14.196

• reaction using 16 (15 minutes vs 24 hours in batch mode; Supporting Information File 1, Table S1, entry 2 and Table 2, entries 1–5. The products 14 and 15, prepared in batch, were isolated in 78 and 68% yield, respectively, and characterized (see Supporting Information File 1, S4). These standards enabled

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• solvents were used as internal standards for 1H NMR (7.26 ppm for CDCl3, 3.31 for CD3OD, 4.79 for D2O, 2.50 for DMSO-d6 and 1.94 ppm for CD3CN) and 13C NMR (77.16 ppm for CDCl3, 49.00 for CD3OD, 39.52 for DMSO-d6 and 118.26 ppm for CD3CN) chemical shift referencing. Abbreviations: s = singlet, d = doublet

Are dispersion corrections accurate outside equilibrium? A case study on benzene

• Tim Gould,
• Erin R. Johnson and
• Sherif Abdulkader Tawfik

Beilstein J. Org. Chem. 2018, 14, 1181–1191, doi:10.3762/bjoc.14.99

• the full potential energy curves. This simple test is not designed to be comprehensive, but rather to interrogate the predictive ability of different approaches. Note that the benchmark set, while slightly inaccurate by modern standards, is predicted to be within 0.1 kcal/mol of more recent benchmarks

Methyl isocyanide as a convertible functional group for the synthesis of spirocyclic oxindole γ-lactams via post-Ugi-4CR/transamidation/cyclization in a one-pot, three-step sequence

• Amarendar Reddy Maddirala and
• Peter R. Andreana

Beilstein J. Org. Chem. 2018, 14, 875–883, doi:10.3762/bjoc.14.74

• chromatographically and spectroscopically pure compounds. 1H and 13C NMR were recorded using a Bruker Avance III 600 MHz. The residual DMSO-d6 1H quintet at δ 2.50 ppm and residual 13C septet at δ 39.51 ppm, CDCl3 1H singlet at δ 7.27 ppm and 13C triplet at δ 77.23 ppm were used as standards for 1H NMR and 13C NMR

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

• Sabine Schuster,
• Beáta Biri-Kovács,
• Bálint Szeder,
• Viktor Farkas,
• László Buday,
• Zsuzsanna Szabó,
• Gábor Halmos and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64

• ][49]. Due to this, the usage of internal standards during the evaluation of new potential candidates might be necessary to ensure comparability with previous results. The cytostatic effect of the novel GnRH-III bioconjugates was determined on HT-29 human colon cancer and MCF-7 human breast cancer cell

• lines by alamarBlue® assay. For a better comparison, the well-studied bioconjugates GnRH-III–[8Lys(Dau=Aoa)] (K1) and GnRH-III–[4Lys(Bu), 8Lys(Dau=Aoa)] (K2) were used as positive controls and internal standards. The corresponding IC50 values were calculated by using nonlinear regression (sigmoidal dose

• standards displayed a higher cellular uptake than the new candidates. This became particularly obvious at lower concentrations (2.5 µM and 10 µM). In accordance with our previous data, the cellular uptake of K2 by HT-29 cells is enhanced in comparison to K1 [29][38]. Furthermore, the cellular uptake by HT