Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

• Hynek Balcar,
• Naděžda Žilková,
• Martin Kubů,
• Michal Mazur,
• Zdeněk Bastl and
• Jiří Čejka

Beilstein J. Org. Chem. 2015, 11, 2087–2096, doi:10.3762/bjoc.11.225

• after centrifugation, the supernatants were analyzed by gas chromatography (GC). In the cross-metathesis experiment, a mixture of methyl oleate (0.25 mmol) and cis-3-hexenyl acetate (0.25 mmol) was added to the suspension of catalyst (1 μmol of Ru) in toluene (1.7 mL) at 30 °C under stirring. The

• ), 19.7 (N-(2-trifluoroacetyl)-2,5-dihydropyrrole), 41.3 (methyl oleate), 33.9 (octadecene), and 57.5 (diester). n-Nonane was used as an internal standard, whenever required. Individual products (all are known compounds) were identified by gas chromatography and mass spectrometry (GC−MS) (ThermoFinnigan

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

Conjugates of methylated cyclodextrin derivatives and hydroxyethyl starch (HES): Synthesis, cytotoxicity and inclusion of anaesthetic actives

• Lisa Markenstein,
• Antje Appelt-Menzel,
• Marco Metzger and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 3087–3096, doi:10.3762/bjoc.10.325

• measurement of the vapor pressure of the sevoflurane by gas chromatography as a function of the CD concentration as already described previously [14][52]. The respective occupancies of the hosts occupancies (the molar ratios of complexed guest vs. host) are listed in Table 2. While native β-CD shows only a

• sevoflurane. The vapor pressure of sevoflurane was determined by head space gas chromatography with a Shimadzu GC-17A GC equipped with a head space unit from Shimadzu, Japan. Vials of 5 mL volume were used, the ratio between gas (V = 3.2 mL) and aqueous (V = 1.8 mL) phase was f = 1.77. Occupancies were

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• by Abreu et al. [65]. Although the recorded mass spectra (HRMS–ESI) for the thus prepared product (±)-3 showed the quasi-molecular peak corresponding to the calculated value, and both the gas chromatography (GC) as well as thin layer chromatography (TLC) showed a single peak and spot respectively

• ether (Et2O) were investigated as the reaction media. Additionally, both lipase catalysts were also screened in neat vinyl acetate (Table 1). The courses of all the enzymatic reactions were monitored by gas chromatography (GC), arrested deliberately after 7 days, and only then their final evolution were

Synthesis of uniform cyclodextrin thioethers to transport hydrophobic drugs

• Lisa F. Becker,
• Dennis H. Schwarz and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 2920–2927, doi:10.3762/bjoc.10.310

• anaesthesia. Keywords: active pharmaceutical ingredient; binding constant; cyclodextrin; derivatization; gas chromatography; sevoflurane; substitution pattern; Introduction Cyclodextrins (CDs) are cyclic oligomers of α-1,4-linked glucose units. Those CDs consisting of 6, 7, and 8 glucose units are called α

• into a mammalian body. Investigation of the inclusion of sevoflurane The inclusion of the anaesthetic sevoflurane by our hosts was investigated by the measurement of the vapour pressure of the guest by gas chromatography as a function of the host concentration as described by Armstrong [51] and

• heating device from Harrick, Pleasantville, New York. The inclusion properties of the host molecules were investigated by head space gas chromatography with a Shimadzu GC-17A GC equipped with a head space unit from Shimadzu, Kyoto, Japan. Vials of 5 mL volume were used, the ratio between gas (V = 3.2 mL

Synthesis of modified cyclic and acyclic dextrins and comparison of their complexation ability

• Kata Tuza,
• László Jicsinszky,
• Tamás Sohajda,
• István Puskás and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2014, 10, 2836–2843, doi:10.3762/bjoc.10.301

• complex of lower binding constant than with β-CD [6]. The helical conformations may act as ‘semicavities’ as proposed by Schurig’s group [7] who found even enantioseparation with the acetylated/silylated G6 and G7 as chiral selectors in gas chromatography. In some cases these acyclodextrins showed similar

Thermal and oxidative stability of the Ocimum basilicum L. essential oil/β-cyclodextrin supramolecular system

• Daniel I. Hădărugă,
• Nicoleta G. Hădărugă,
• Corina I. Costescu,
• Ioan David and
• Alexandra T. Gruia

Beilstein J. Org. Chem. 2014, 10, 2809–2820, doi:10.3762/bjoc.10.298

• conditions using gas chromatography–mass spectrometry (GC–MS). The occurrence of harmful degradation compounds in raw basil essential oil and in the recovered product of the β-CD complex subjected to thermal/oxidative degradation has been comparatively evaluated. Results and Discussion Ocimum basilicum L

• encapsulated in β-CD) The analysis of the raw and recovered material from the β-CD complex O. basilicum L. essential oil, that is, the non-degraded or thermal/oxidative degraded samples, was performed by gas chromatography coupled with mass spectrometry (GC–MS). A GC Hewlett Packard HP 6890 Series gas

Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene

• Ludmilla Lumholdt,
• Sophie Fourmentin,
• Thorbjørn T. Nielsen and
• Kim L. Larsen

Beilstein J. Org. Chem. 2014, 10, 2743–2750, doi:10.3762/bjoc.10.290

• organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used

• and five other benzene-based volatile organic compounds (VOCs) (see Table 2) were chosen as model compounds. Their uptake by the ACD-functionalised PP was characterised using static headspace gas chromatography (SH-GC). These VOCs have been shown in the literature to effectively form stable inclusion

• measured by static headspace gas chromatography after a minimum equilibration time of 12 hours. After this, equilibrium between the three phases of the VOCs, gaseous, aqueous, and complexed, is assumed to be established according to: where VOCg and VOCaq are the VOCs present in the gaseous and aqueous

Hindered aryl bromides for regioselective palladium-catalysed direct arylation at less favourable C5-carbon of 3-substituted thiophenes

• Rongwei Jin,
• Charles Beromeo Bheeter and
• Henri Doucet

Beilstein J. Org. Chem. 2014, 10, 1239–1245, doi:10.3762/bjoc.10.123

• for 20 h. After cooling, the crude reaction mixture was analysed by gas chromatography and 1H NMR to determine the conversion of the aryl bromide and the regioselectivity of the arylation. The solvent was removed by heating under vacuum, then the residue was charged onto a silica gel column. tert

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)

• Armin Tröger,
• Teris A. van Beek,
• Martinus E. Huigens,
• Isabel M. M. S. Silva,
• Maarten A. Posthumus and
• Wittko Francke

Beilstein J. Org. Chem. 2014, 10, 767–773, doi:10.3762/bjoc.10.72

• of 8 showed an E/Z-ratio of ca. 2:1 and was highly dominated by the anti-isomers (see Supporting Information File 1, Figure S1). The E/Z-isomers of the two pairs of diastereomers could be separated by gas chromatography. Analysis by coupled gas chromatography/mass spectrometry (GC–MS) showed the 70

• products by enantioselective gas chromatography. However, ozonolysis of a natural sample [29] containing the two compounds, followed by reductive work-up, would yield syn,syn-2,4,6-trimethylnonanol, the enantiomers of which can be easily separated by using heptakis-[2,3-di-O-methyl-6-O-(tert

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

• Phei Li Lau,
• Ray W. K. Allen and
• Peter Styring

Beilstein J. Org. Chem. 2013, 9, 2886–2897, doi:10.3762/bjoc.9.325

• catalyst, 2% palladium on silica was purchased from Johnson Matthey. Gas chromatography–mass spectra GC–MS analyses (EI and CI modes) were performed using a PerkinElmer GC–MS with a 30 m × 0.25 mm × 0.25 μm Phenomenex-ZB5 column by Jane Stanbra and Simon Thorpe in the Department of Chemistry, The

• . The resulting organic mixture (top layer) was then withdrawn and dried over magnesium sulfate then analysed by gas chromatography using a Varian 3900 GC with reference to standard solutions of trans-4-methoxystilbene. Continuous flow reactions Particles of the catalyst, 2% Pd on silica, (250 mg

• containing the mixture of products. The samples were then analysed by gas chromatography (GC) and GC-mass spectrometry (GC–MS) against known calibration standards of the starting material and products. At the end of reaction, the system tubing and reactor were flushed with CO2 and the organic solvent mixture

Flow synthesis of phenylserine using threonine aldolase immobilized on Eupergit support

• Jagdish D. Tibhe,
• Hui Fu,
• Timothy Noël,
• Qi Wang,
• Jan Meuldijk and
• Volker Hessel

Beilstein J. Org. Chem. 2013, 9, 2168–2179, doi:10.3762/bjoc.9.254

• were determined by HPLC analysis of the aqueous phase, while conversion of benzaldehyde was determined from analysis of the organic layer using gas chromatography. Since no byproducts could be detected, the degree of conversion reflected the yield of phenylserine formation. Flow reactions A Teflon

Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping

• Skrollan Stockinger and
• Oliver Trapp

Beilstein J. Org. Chem. 2013, 9, 1837–1842, doi:10.3762/bjoc.9.214

• Skrollan Stockinger Oliver Trapp Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany 10.3762/bjoc.9.214 Abstract A new approach for the investigation of a higher-order reaction by on-column reaction gas chromatography is

• ; cycloaddition; Diels–Alder reaction; flow chemistry; gas chromatography; on-column reaction gas chromatography; Introduction The combination of synthesis and analysis in a single experiment offers many advantages. Time-consuming steps, i.e. work-up and separation of the reaction products, can be minimized, and

• , which is discussed in the present contribution. Here, we use a focusing technique to concentrate and stop separating several substances in a single column section to study higher-order reactions and to increase the conversion in on-column reaction gas chromatography (ocRGC). The major challenge in

Space filling of β-cyclodextrin and β-cyclodextrin derivatives by volatile hydrophobic guests

• Sophie Fourmentin,
• Anca Ciobanu,
• David Landy and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1185–1191, doi:10.3762/bjoc.9.133

• Saarbrücken, Germany 10.3762/bjoc.9.133 Abstract The inclusion of volatile derivatives of benzene and cyclohexane in β-cyclodextrin (β-CD), hydroxypropyl-β-CD, and hydrophilic β-CD-thioethers was investigated by static headspace gas chromatography (HS-GC) and molecular modelling. The obtained binding

• constants strongly increase with the amount of space filling of the CD cavity and the salt concentration. β-CD thioethers show a 3–10 times higher binding potential than native β-CD. Keywords: cyclodextrins; inclusion compound; molecular modelling; space filling; static headspace gas chromatography; vapor

• gas chromatography (HS-GC) is a highly sensitive technique, it allows the investigation of the complexation of volatile guests in CD at very low concentrations, where guests, as well as their inclusion compounds, are still soluble in water [19][34][35][36]. Complexation of a guest is detected

3-Pyridylnitrene, 2- and 4-pyrimidinylcarbenes, 3-quinolylnitrenes, and 4-quinazolinylcarbenes. Interconversion, ring expansion to diazacycloheptatetraenes, ring opening to nitrile ylides, and ring contraction to cyanopyrroles and cyanoindoles

• Curt Wentrup,
• Nguyen Mong Lan,
• Adelheid Lukosch,
• Pawel Bednarek and
• David Kvaskoff

Beilstein J. Org. Chem. 2013, 9, 743–753, doi:10.3762/bjoc.9.84

• visible light where required. Analytical gas chromatography used a 10% OV 17 column programmed at 120–180 °C at 2°/min with N2 as carrier gas at 0.6 bar. Preparative gas chromatography used a 20% Carbowax column at 200 °C with H2 as carrier gas at 60 mL/min. Materials 3-Azidopyridine (9) [34][35], 2-(5

Intramolecular carbonickelation of alkenes

• Rudy Lhermet,
• Muriel Durandetti and
• Jacques Maddaluno

Beilstein J. Org. Chem. 2013, 9, 710–716, doi:10.3762/bjoc.9.81

• starting material is monitored by gas chromatography. The mixture is hydrolyzed with water (10 mL), diluted with Et2O (10 mL), and then filtered through celite. The aqueous layer is extracted with Et2O (2 × 10 mL), and then the combined organic layers are washed with water (3 × 10 mL) and brine (2 × 10 mL

Chemoenzymatic synthesis and biological evaluation of enantiomerically enriched 1-(β-hydroxypropyl)imidazolium- and triazolium-based ionic liquids

• Paweł Borowiecki,
• Małgorzata Milner-Krawczyk and
• Jan Plenkiewicz

Beilstein J. Org. Chem. 2013, 9, 516–525, doi:10.3762/bjoc.9.56

• polymerization [36], as chiral phase for gas chromatography [37], or as chiral differentiating solvents for spectroscopic investigations [38][39] is far from being exhausted. CILs can also act as a tool for organizing the structure of solid polymeric electrolytes (SPE), playing the triple role as plasticizer

N-Heterocyclic carbene–palladium catalysts for the direct arylation of pyrrole derivatives with aryl chlorides

• Ismail Özdemir,
• Nevin Gürbüz,
• Nazan Kaloğlu,
• Öznur Doğan,
• Murat Kaloğlu,
• Christian Bruneau and
• Henri Doucet

Beilstein J. Org. Chem. 2013, 9, 303–312, doi:10.3762/bjoc.9.35

• mmol, see Table 1–5) and DMAc (3 mL) were added, and the Schlenk tube was purged several times with argon. The Schlenk tube was placed in a preheated oil bath at 150 °C, and the reaction mixture was stirred for 20 h. Then, the reaction mixture was analysed by gas chromatography to determine the

Iron-containing mesoporous aluminosilicate catalyzed direct alkenylation of phenols: Facile synthesis of 1,1-diarylalkenes

• Satyajit Haldar and
• Subratanath Koner

Beilstein J. Org. Chem. 2013, 9, 49–55, doi:10.3762/bjoc.9.6

• 0.80 wt %, respectively. Initially, the Fe-Al-MCM-41-catalyzed reaction of phenylacetylene and phenol was carried out in different solvent media. The progress of the reaction was monitored by analyzing the products with the help of gas chromatography (Table 1). Amongst various solvents, such as

• added to a mixture of phenol (1.5 mmol) and Fe-Al-MCM-41 (0.065 g) in 2 mL of cyclohexane. The mixture was stirred at 80 °C in an oil bath. To study the progress of the reaction, the products were collected at different time intervals and identified and quantified by gas chromatography. After completion

Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• relative yields determined by gas chromatography given in Scheme 3; ca. 10% of the reaction mixture was unreacted starting material 2. Whereas the structure assignments of 14 and 20 are based on the usual spectroscopic data (see Experimental section; Supporting Information File 1) and are unequivocal, for

• 17 and 19 only GC–MS data were available, and the given structures are hence speculative and rest only on their mass spectra. Hydrocarbon 14 was obtained in 80% purity by preparative gas chromatography; its complete separation from 17 failed. The bisallyl derivative 20 was isolated in analytically

• pure form by preparative gas chromatography. All hydrocarbons are colorless oils that, even at −15 °C (deep freeze), are stable for a limited time only. A simple rationalization of the product formation, in which 14 and 17 are the primary products, is given in Scheme 3. Hydrocarbon 14 is the direct

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• distillation is difficult because they are unstable und possess similar physical constants. If pure 21 were needed, 2 can be removed from the reaction mixture by trapping it by a Diels–Alder reaction (see Section 1.4.1 below). The analytically pure hydrocarbons were obtained by preparative gas chromatography

• isomers and secondary products are produced and their separation is difficult. Nevertheless, to determine the spectroscopic properties of these C7H8-hydrocarbons, they can be (and have been) separated by preparative gas chromatography. In preparative chemistry one of the most frequently used conjugated

Polysiloxane ionic liquids as good solvents for β-cyclodextrin-polydimethylsiloxane polyrotaxane structures

• Narcisa Marangoci,
• Rodinel Ardeleanu,
• Laura Ursu,
• Constanta Ibanescu,
• Maricel Danu,
• Mariana Pinteala and
• Bogdan C. Simionescu

Beilstein J. Org. Chem. 2012, 8, 1610–1618, doi:10.3762/bjoc.8.184

• been used for capillary gas chromatography [25][26] and as biocides [27]. Furthermore, one of our interests is to combine the properties of polydimethylsiloxanes with the versatility of synthetic approaches in designing well-defined macromolecular systems [17][21][27]. In this context, we synthesized

A novel asymmetric synthesis of cinacalcet hydrochloride

• Veera R. Arava,
• Laxminarasimhulu Gorentla and
• Pramod K. Dubey

Beilstein J. Org. Chem. 2012, 8, 1366–1373, doi:10.3762/bjoc.8.158

• analysis of 8 and 15 in gas chromatography. Both were clearly separated and 15 was absent in 8. The impurity 14 was further structurally assigned by its synthetic preparation starting from 15. The obtained propionic acid 10 was esterified to its methyl ester 11 with methanol and thionyl chloride under

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part II: Iridomyrmecins

• Robert Hilgraf,
• Nicole Zimmermann,
• Lutz Lehmann,
• Armin Tröger and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1256–1264, doi:10.3762/bjoc.8.141

• , all eight stereoisomers of trans-fused iridomyrmecins were synthesized starting from the enantiomers of limonene. Combined gas chromatography and mass spectrometry including enantioselective gas chromatography revealed that volatiles released by the endohyperparasitoid wasp Alloxysta victrix contain

• following a strategy similar to our route leading to trans-fused dihydronepetalactones [1]. The realization of this task and the unambiguous structure assignment of the natural products Y and Z is subject of the present paper. Results and Discussion Upon coupled gas chromatography/mass spectrometry (GC/MS

• ]. Gas chromatography coupled with chemical ionization mass spectrometry (GC/CIMS) proved the molecular mass of the target compounds to be [M]+ = 168, while high resolution mass spectrometry (GC/HRMS) showed their atomic composition to be C10H16O2, confirming the compounds to be isomers of

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part I: Dihydronepetalactones

• Nicole Zimmermann,
• Robert Hilgraf,
• Lutz Lehmann,
• Daniel Ibarra and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1246–1255, doi:10.3762/bjoc.8.140

• of the other chiral centers during the synthesis. Basically, this approach could also be used for the synthesis of enantiomerically pure trans-fused iridomyrmecins. Using synthetic reference samples, the combination of enantioselective gas chromatography and mass spectrometry revealed that volatiles

• Alloxysta victrix by coupled gas chromatography/mass spectrometry (GC/MS). Figure 1 shows one major component and several trace components which could be identified as 6-methyl-5-hepten-2-one (1), neral (2), geranial (3), actinidine (4), and geranylacetone (5). Bioassays revealed the main compound 1 to be

• the subject of the present paper. Results and Discussion Apart from a couple of known acyclic terpenoids (Figure 1), analysis by gas chromatography coupled with mass spectrometry (GC/MS) revealed the presence of an unknown minor component X in both sexes of Alloxysta victrix. Chemical ionization