Pd(OAc)₂/Ph₃P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles

• Dominik Kellner,
• Maximilian Weger,
• Andrea Gini and
• Olga García Mancheño

Beilstein J. Org. Chem. 2017, 13, 1807–1815, doi:10.3762/bjoc.13.175

• ” and a GC–MS “QP-2010 SE”. Exact masses (HRMS) were recorded on an Agilent Q-TOF 6540 UHD spectrometer. Commercially available reagents were used without further purification. Pd-catalyzed dimerization of isoprene The reaction was performed under nitrogen in a screw-cap vial. Pd(OAc)2 (11.2 mg, 0.05

18-Hydroxydolabella-3,7-diene synthase – a diterpene synthase from Chitinophaga pinensis

• Jeroen S. Dickschat,
• Jan Rinkel,
• Patrick Rabe,
• Arman Beyraghdar Kashkooli and
• Harro J. Bouwmeester

Beilstein J. Org. Chem. 2017, 13, 1770–1780, doi:10.3762/bjoc.13.171

• based on the identification of this compound and its Cope rearrangement product β-elemene (2) formed by the thermal impact during GC–MS analysis [19] in E. coli headspace extracts under heterologous expression of the terpene synthase gene (Scheme 1). Here we present the diterpene synthase activity of

• -, sesqui- and diterpene activity by incubation with geranyl (GPP), farnesyl (FPP) and geranylgeranyl diphosphate (GGPP) as substrates, which yielded a single product 3 only from GGPP, but no products from FPP and GPP as demonstrated by GC–MS analysis (Figure 1). The mass spectrum of 3 showed a molecular

• in all treatments to suppress endogenous silencing of N. benthamiana upon agroinfiltration. No difference was found by GC–MS in EtOAc extracts of N. benthamiana leaves expressing an empty vector or HdS, while the chromatogram of an extract obtained from HdS-mit expressing leaves revealed an

An efficient Pd–NHC catalyst system in situ generated from Na₂PdCl₄ and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

• Nan Sun,
• Meng Chen,
• Liqun Jin,
• Wei Zhao,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168

• standard. Mass spectrometry data (MALDI–TOF) of the three imidazolium salts L1–L3 were collected on a Bruker ultrafleXtreme mass spectrometer. Low-resolution mass analyses were performed on a Thermo Trace ISQ GC–MS instrument in EI mode (70 eV) or a Thermo Scientific ITQ 1100TM mass spectrometer in ESI

An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

• Carolina S. García,
• Paula M. Uberman and
• Sandra E. Martín

Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166

• chromatograph with a flame ionization detector, and equipped with the following columns: HP-5 25 m × 0.20 mm × 0.25 μm column. 1H NMR and 13C NMR were conducted on a high resolution spectrometer Bruker Advance 400, in CDCl3 as solvent. Gas chromatographic/mass spectrometer analyses were carried out on a GC–MS

• stilbene products 3–15 were purified by silica gel column chromatography. The products were characterized by 1H NMR, 13C NMR, and GC–MS. All spectroscopic data were in agreement with those previously reported for the following compounds: (E)-1-(4-styrylphenyl)ethanone (3) [64], (E)-phenyl(4-styrylphenyl

• by silica gel column chromatography. The products were characterized by 1H NMR, 13C NMR, and GC–MS. All the spectroscopic data were in agreement with those previously reported for the following compounds: (E)-1,1'-(ethene-1,2-diylbis(4,1-phenylene))diethanone (17) [68] and (E)-1,2-bis(3,5

Photocatalyzed synthesis of isochromanones and isobenzofuranones under batch and flow conditions

• Manuel Anselmo,
• Lisa Moni,
• Hossny Ismail,
• Davide Comoretto,
• Renata Riva and
• Andrea Basso

Beilstein J. Org. Chem. 2017, 13, 1456–1462, doi:10.3762/bjoc.13.143

• carbonyl oxygen. Compound 9 immediately afforded isochromanone 4d (60%) upon exposure to water (Scheme 4). Careful control of the isolation procedures (see Supporting Information File 1) allowed us to isolate 9 and identify it through GC–MS and 1H NMR experiments (the compound, however, partially

Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin

• Ana Franco,
• Sudipta De,
• Alina M. Balu,
• Araceli Garcia and
• Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1439–1445, doi:10.3762/bjoc.13.141

• nm × 0.5 μm and a flame ionization detector (FID). The results were finally confirmed by GC–MS. N2 isotherms of (a) RGO, (b) Fe/RGO, and (c) Co/RGO. SEM images of (a and b) RGO, (c) 1% Fe/RGO, and (d) 1% Co/RGO. TEM micrographs at different magnifications of (a and b) RGO, (c and d) 1% Fe/RGO, and (e

Use of costic acid, a natural extract from Dittrichia viscosa, for the control of Varroa destructor, a parasite of the European honey bee

• Kalliopi Sofou,
• Demosthenis Isaakidis,
• Apostolos Spyros,
• Anita Büttner,
• Athanassios Giannis and
• Haralambos E. Katerinopoulos

Beilstein J. Org. Chem. 2017, 13, 952–959, doi:10.3762/bjoc.13.96

• -methylaromadendrin and 7-O-methylaromadendrin-3-acetate (Figure 4) by GC–MS analysis. To the best of our knowledge, these structures are reported for the first time as components of D. viscosa. The conditions of the GC–MS experiment were as follows [51]: The essential oil and extracts were analyzed by GC–MS on a

• Shimadzu GC-17 A gas chromatograph coupled with a Shimadzu GC–MS-QP 5050 mass selective detector. A Supelco SBP-5 fused silica capillary column of 30 m, 0.25 mm i.d. (0.25 μm film thickness) was used for the analysis. The carrier gas was helium (He) at a flow rate of 0.9 mL/min. The injector and the

• mass spectra using the NIST 64 and NIST 120 GC–MS libraries and the comparison of their retention times with those of reference. Screening tests. The experiment was conducted in a completely randomized design under laboratory conditions in five replications. In each replication 20, 60, or 100

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• ). However, with 6-bromohex-1-ene the yield of compound 5d dropped to 41% (Table 3, entry 5) and 2-methyltetrahydro-2H-selenopyran was detected by GC–MS. This indicates a possible competitive intramolecular addition reaction between the selenium atom-centered radical and the alkenyl moiety. The reaction with

• -substituted product 5p was only detected in traces by GC–MS suggesting that this product cyclized in the reaction medium to afford indole 9 (Table 4, entry 9). On the other hand, when o-MeO-substituted phenylacetylene 6j was employed the corresponding selenyl-substituted product 5q was isolated in 51% yield

• ]. Therefore, we can explain the formation of indole 9 by oxidation of 5p, generated in situ as described above, to afford the iminium intermediate 12. Hydrolysis of the latter liberates the secondary amine 13 (Scheme 7). This intermediate was detected by GC–MS in traces. Finally, the presence of base in

Substitution of fluorine in M[C₆F₅BF₃] with organolithium compounds: distinctions between O- and N-nucleophiles

• Anton Yu. Shabalin,
• Nicolay Yu. Adonin and
• Vadim V. Bardin

Beilstein J. Org. Chem. 2017, 13, 703–713, doi:10.3762/bjoc.13.69

• polyfluoroaryltrifluoroborates by hydrogen in alcohol at elevated temperature and obtaining the corresponding polyfluoroarenes in high yields. The latter are more simple substances and available for analysis by NMR spectroscopy, GC–MS and HRMS methods [33]. Heating a mixture of 6-K, 7-K, 8-K and 9-K in MeOH leads to conversion

• ]. The structures of 18 and 19 are consistent with 19F NMR, GC–MS and HRMS data. For characterization of the products derived from 1-K and PhLi we performed the hydrodeboration of a mixture of 1-K, 10-K and 11-K by stirring it in 2-methoxyethanol under reflux. After evaporation of the alcohol and C6F5H

• , the known 2,3,5,6-tetrafluorobiphenyl (14) [35][36] and 2,3,4,5-tetrafluorobiphenyl (15) [35][36] were obtained (Scheme 6). Then a mixture of borates 10-K, 11-K, 12-K, and 13-K was converted to biphenyls 14, 15, and terphenyls 20, 21, respectively, and characterized by 19F NMR spectroscopy, GC–MS and

Ultrasound-promoted organocatalytic enamine–azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones

• Gabriel P. Costa,
• Natália Seus,
• Juliano A. Roehrs,
• Raquel G. Jacob,
• Ricardo F. Schumacher,
• Thiago Barcellos,
• Rafael Luque and
• Diego Alves

Beilstein J. Org. Chem. 2017, 13, 694–702, doi:10.3762/bjoc.13.68

• spectra (13C NMR) were obtained at 100 MHz on Bruker DPX 400 spectrometer. Chemical shifts are reported in ppm, referenced to the solvent peak of CDCl3. Low-resolution mass spectra were obtained with a Shimadzu GC-MS-QP2010 mass spectrometer. High resolution mass spectra (HRMS) were recorded on a Bruker

Unpredictable cycloisomerization of 1,11-dien-6-ynes by a common cobalt catalyst

• Abdusalom A. Suleymanov,
• Dmitry V. Vasilyev,
• Valentin V. Novikov,
• Yulia V. Nelyubina and
• Dmitry S. Perekalin

Beilstein J. Org. Chem. 2017, 13, 639–643, doi:10.3762/bjoc.13.62

• protons. On the basis of 1H–1H and 1H–13C correlation NMR spectra as well as GC–MS analysis we had assigned the structures of these products as the cyclopropane derivatives with internal 4 and exocyclic 5 double bonds (Scheme 2). Our spectral data correlate well with that of similar compounds, which were

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• product structures by gas-chromatography/mass spectrometry (GC–MS) and liquid chromatography (LC)–MS. Review Biosynthesis of complex polyketides by modular PKSs and stereochemical considerations The reduced or complex class of polyketides is assembled in bacteria by gigantic multienzymes called polyketide

• )- and (4S)-[4-2H]NADPH) with modules 1, 2, 5 and 6 from the DEBS PKS and analysis of the resulting products by GC-MS, showed that all of the KRs are specific for the 4′-pro-S hydride of the nicotinamide cofactor [52][53], as found for fatty acid biosynthesis [54][55]. Given the high sequence similarity

• group because it mimics the terminal portion of the phosphopantetheine cofactor to which the chain extension intermediates are normally tethered. The stereochemistry of the reduction products was typically established by GC–MS and comparison to authentic synthetic standards, or alternatively by LC–MS

Continuous N-alkylation reactions of amino alcohols using γ-Al₂O₃ and supercritical CO₂: unexpected formation of cyclic ureas and urethanes by reaction with CO₂

• Emilia S. Streng,
• Darren S. Lee,
• Michael W. George and
• Martyn Poliakoff

Beilstein J. Org. Chem. 2017, 13, 329–337, doi:10.3762/bjoc.13.36

• Gases (99.8%). The γ-alumina (PURALOX NWa155) was supplied by SASOL. It was sieved before use, to obtain the desired particle size (125–170 μm), which was used as the catalyst. Reaction mixtures were analysed using GC, GC–MS, 1H and 13C NMR. Compounds 1a–c, 4, 9, 10, 13, 14, 16 were obtained from

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• reduction by NaH [81]. Reductive decyanation catalyzed by nickel nanoparticles. Yields are given in weight % from GC–MS data [85]. Decyanation of 2-cyanobenzo[b]thiophene [87]. Simplified pathways involved in transition-metal-promoted reductive decyanations [93][95]. Fe-catalyzed reductive decyanation

• A, 14 examples, yield ≥ 20% and 1 synthetic application; method B, 12 examples, yield ≥ 17% and 1 synthetic application). Yields determined by GC–MS and 1H NMR spectroscopy [106][107]. Proposed catalytic cycle for the nickel complex 58 catalyzed decyanation (method A). Only the cycle for 63 is shown

Diels–Alder reactions of myrcene using intensified continuous-flow reactors

• Christian H. Hornung,
• Miguel Á. Álvarez-Diéguez,
• Thomas M. Kohl and
• John Tsanaktsidis

Beilstein J. Org. Chem. 2017, 13, 120–126, doi:10.3762/bjoc.13.15

• analyzed by GC–FID and GC–MS; details for both can be found in Supporting Information File 1. The GC–FID results were also used to confirm NMR conversions and to calculate GC-based yields. Batch Diels–Alder reaction The following procedure is typical for the preparation of the Diels–Alder adduct of myrcene

Direct arylation catalysis with chloro[8-(dimesitylboryl)quinoline-κN]copper(I)

• Sem Raj Tamang and
• James D. Hoefelmeyer

Beilstein J. Org. Chem. 2016, 12, 2757–2762, doi:10.3762/bjoc.12.272

• equivalents KO(t-Bu) (Table 1, entry 1). After 10 hours the yield of biphenyl was 94% according to GC–MS analysis. A control reaction (Table 1, entry 4) of iodobenzene with benzene/DMF (10:1 v/v) using 2 mol % Cu(I)Br and 30 equivalents KO(t-Bu) gave 5% yield of biphenyl after 10 hours. Reactions performed in

• heterocoupling pathway. The coupling of benzene with p-iodoanisole at 2 mol % loading of catalyst 2 was evaluated (Table 1, entry 2). We were pleased to find that the reaction yielded 4-methoxybiphenyl according to GC–MS analysis, and the isolated yield after flash column chromatography was 77%. Encouraged by

• ]. All organic reagents and solvents were obtained from commercial sources and used without further purification. A GCMS-QP2010SE gas chromatograph–mass spectrometer (Shimadzu Corp., Kyoto, Japan) was used for GC–MS analyses. NMR spectra were recorded on an Avance 400 MHz spectrometer (Bruker, Billerica

Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

• Markus Menke,
• Pardha Saradhi Peram,
• Iris Starnberger,
• Walter Hödl,
• Gregory F.M. Jongsma,
• David C. Blackburn,
• Mark-Oliver Rödel,
• Miguel Vences and
• Stefan Schulz

Beilstein J. Org. Chem. 2016, 12, 2731–2738, doi:10.3762/bjoc.12.269

• synthesis of the identified compounds for biological testing. Because of the small amount of natural material available, only GC–MS investigations can be used to identify the compounds. The analysis revealed unsaturated macrocyclic lactones to be major constituents of the secretion of the cinnamon-bellied

• EI mass spectra of unsaturated macrolactones, and 3) show how ring-closing metathesis reaction conditions can be selected to obtain either pure compounds or a library of compounds useful for evaluation of their mass spectra. Results and Discussion The GC–MS analysis of a gular gland extract of

• isomerized mixtures constitute a library of closely related macrolides differing slightly in position of double bonds and ring size. With the diagnostic mass spectrometric ions discussed above, each compound can be assigned a structure after GC–MS analysis. These mass spectra together with the gas

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

• Ming Liu,
• Jan C. Namyslo,
• Martin Nieger,
• Mika Polamo and
• Andreas Schmidt

Beilstein J. Org. Chem. 2016, 12, 2673–2681, doi:10.3762/bjoc.12.264

• range of 400 to 4000 cm−1. The mass spectra were obtained with a Varian 320 MS Triple Quad GC/MS/MS instrument with a Varian 450-GC. All electrospray ionisation mass spectra (ESIMS) were measured with a Hewlett-Packard/Agilent LCMSD series HP 1100 spectrometer with APIES. The compound samples were

A detailed view on 1,8-cineol biosynthesis by Streptomyces clavuligerus

• Jan Rinkel,
• Patrick Rabe,
• Laura zur Horst and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 2317–2324, doi:10.3762/bjoc.12.225

• chromatography and used to convert both (R)- and (S)-(1-2H)GPP into (2H)-1 (in agreement with the findings described in reference [28], 1 is the only product from unlabelled GPP as was shown by GC–MS, Figure S2, Supporting Information File 1). The obtained products were analysed by HSQC spectroscopy (Figure 2

• , overlaid with 400 μL (2H6)benzene and further incubated overnight. The organic phase was separated, dried over MgSO4 and directly analysed by GC–MS and NMR. Incubation experiment with (2-13C)GPP Enzyme purification starting from an E. coli expression culture (0.5 L) was performed as described above. The

• was analysed directly by GC–MS and NMR. NMR spectroscopy To record NMR spectra, instruments AV Avance DMX-500 (500 MHz), DPX-400 (400 MHz) and AV III HD Cryo (700 MHz) from Bruker were used. Solvent signals were used to reference the spectra (1H NMR, residual proton signals: (2H6)benzene δ = 7.16; 13C

Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products

• Manuela Oliverio,
• Paola Costanzo,
• Monica Nardi,
• Carla Calandruccio,
• Raffaele Salerno and
• Antonio Procopio

Beilstein J. Org. Chem. 2016, 12, 2222–2233, doi:10.3762/bjoc.12.214

• activated and gave rise to moderate yields as in a typical equilibrium system. The reactions were monitored by TLC or GC–MS until the reagent disappeared and the work-up procedure was optimized in order to minimize the wastes of the process. Namely the reaction mixture was reacted with ethanol in order to

• quantitative conversion was registered and the obtained mixture of different acetylated derivatives was fully identified by GC–MS (see Supporting Information File 1). In this last case the change of the P-program was ineffective in increasing the yield of 9a in respect to the other acetylated forms (data not

• seal. Reactions were monitored by TLC using silica plates 60-F264 on alumina, commercially available from Merk. GC–MS spectra were recorded on a GC–MS Thermo Scientific workstation, formed by a Focus GC (30-m VARIAN-VF-5ms, 0.25 mm diameter capillary column, working on spitless mode, 1.2 mL/min He as

Regiocontroled Pd-catalysed C5-arylation of 3-substituted thiophene derivatives using a bromo-substituent as blocking group

• Mariem Brahim,
• Hamed Ben Ammar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2016, 12, 2197–2203, doi:10.3762/bjoc.12.210

• expected coupling products 2–4 were obtained in moderate yields. On the other hand, with 4-bromoanisole as an electron-rich aryl bromide, the desired C5-arylated 2-bromothiophene could not be detected by GC–MS analysis of the crude mixture, and a large amount of unreacted 4-bromoanisole was recovered

Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties

• Pierre Boufflet,
• Sebastian Wood,
• Jessica Wade,
• Zhuping Fei,
• Ji-Seon Kim and
• Martin Heeney

Beilstein J. Org. Chem. 2016, 12, 2150–2163, doi:10.3762/bjoc.12.205

• THF) dropwise. After 30 min, the resulting Grignard monomer solution (0.28 M in THF) was ready for use as indicated by the near total consumption of starting material (<3% remaining by quenching a sample with methanol and analysing by GC–MS). Synthesis of P3OT-b-F-P3OT 2:1 In a sealed dry 2–5 mL

Solvent-free synthesis of novel para-menthane-3,8-diol ester derivatives from citronellal using a polymer-supported scandium triflate catalyst

• Lubabalo Mafu,
• Ben Zeelie and
• Paul Watts

Beilstein J. Org. Chem. 2016, 12, 2046–2054, doi:10.3762/bjoc.12.193

• C0 = quaternary carbon. Gas chromatography (GC–MS) spectrometry was performed on a HP F5890 series LL plus gas chromatograph coupled to an HP 5972 series mass selective detector. The GC was equipped with a HP-5 MS capillary column (30 mm × 0.25 mm i.d.) and ultra-high purity helium (99.999%) carrier

• : NMR, IR and GC–MS spectra of synthesized compounds. Acknowledgements We wish to thank InnoVenton: Institute of Chemical Technology and the National Research Fund (NRF) for their financial support.

Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines

• David R. Chisholm,
• Garr-Layy Zhou,
• Ehmke Pohl,
• Roy Valentine and
• Andrew Whiting

Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174

• %) according to GC–MS analysis, and the iodinated product 2 was difficult to isolate by chromatography. In light of these results, bromination was conducted with the aim of synthesising the corresponding aryl iodide 2 by halogen exchange (Scheme 3). After careful optimisation of the reaction conditions, the

Mechanistic investigations on six bacterial terpene cyclases

• Patrick Rabe,
• Thomas Schmitz and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1839–1850, doi:10.3762/bjoc.12.173

• cloning by homologous recombination in yeast, followed by the heterologous expression in Escherichia coli, direct headspace sampling using a closed-loop stripping apparatus (CLSA) and compound identification by GC–MS [32][33]. Here we report on the purification of six of these bacterial sesquiterpene

• , Figure 1) by GC–MS analysis (Figure S1, Supporting Information File 1) [32], while the enzyme incubations with geranyl diphosphate (GPP) and geranylgeranyl diphosphate (GGPP) gave no products. Although 1 was isolated from vetiver oil (Vetiveria zizanioides, Gramineae) nearly five decades ago [38], the

• identified as T-muurolol by GC–MS [32], besides minor amounts of α-muurolene and δ-cadinene (Figure S1, Supporting Information File 1). The 13C NMR and 13C-DEPT135 spectra of purified 2 exhibited signals for four methyl groups, four methylene groups, five methine (four sp3-CH and one sp2-CH) as well as two