New structural aspects of 3-vinyl-1H-indoles for predicting the outcome of Diels-Alder reactions

Summary Some selected 3-vinyl-1H-indoles have been synthesised and the first¹³C-NMR studies performed; in addition He(I) photoelectron spectra and the results of perturbation MO calculations of some examples of this class of compounds are presented. The molecular characteristics obtained thereby can be used to predict the results of [4s+2s]-cycloaddition reactions with 3-vinylindoles.

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Neue strukturelle Aspekte von 3-Vinylindolen zur Vorhersage der Reaktionsergebnisse bei Diels-Alder-Reaktionen

Zusammenfassung An selektiv synthetisierten 3-Vinyl-1H-indolen werden erstmals¹³C-NMR-spektroskopische Studien durchgeführt und exemplarisch an einigen Vertretern dieser Strukturklasse He(I)-Photoelektronenspektren sowie Ergebnisse von Störungs-MO-Rechnungen vorgestellt. Die daraus gewonnenen Moleküleigenschaften können zur Vorhersage des Reaktionsausganges von [4s+2s]-Cycloadditionen mit 3-Vinylindolen verwendent werden.

     

RP-LC Determination of Rutin in Amaranthus spinosus Linn. Whole Plant Powder

A simple, reproducible and efficient reverse phase high performance liquid chromatographic method has been developed for the determination of rutin in whole plant powder of Amaranthus spinosus Linn. The analysis was done with Waters Cosmosil C₁₈ column (150 × 4.6 mm i.d., 5 μm particle size) as stationary phase at a wavelength of 361 nm for detection and determination. The proposed HPLC method was validated for linearity, accuracy, precision and limit of quantitation.     

Spectres RMN-13C de Quelques Medicaments a Action Parasymatholytique Peripferique Derives du 1,3-Propanol

Abstract

Les spectres RMN-¹³ C de quelques dérivés du propanol substitué en 1,3 ont été étudiés. Une attribution des signaux est propasée.

Carbon-13 nuclear magnetic resonance spectra of some substituted 1, 3-propanols have been recorded and fully assigned.     

Ketendithioacetal-S-imide

Starting from 2-isopropylidene-1,3-dithiane, various ketene-dithioacetal-S-imides have been prepared and characterized by¹H- and¹³C-NMR spectra.

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Ketendithioacetal-S-imideKurze Mitteilung

     

Identification Des Produits De La Reduction Electrochimique d'Un Nouvel Antiinflammatoire: Le Piroxicam

Abstract

The electrochemical reduction of piroxicam has been investigated on a mercury pool in acidic and alcaline media.

After exhaustive electrolysis, the extraction followed by chromatographic separation of the reaction products gives the reduced compounds which have been identified by spectroscopic techniques. From the analysis of the NMR ¹H, ¹³C and IR spectra and the results of our preceding electrochemical investigation, the polarographic behaviour of piroxicam has been elucidated. The process occurs by the irreversible reduction of the double bond of the enol function over the total pH range investigated. However, in alkaline and highly acidic solutions, a preceding two-electron step occurs, giving rise to the opening of the thiazine ring.     

Ultrasound-promoted coupling of aryl and heteroaryl halides in the presence of lithium wire

Summary Although sonochemical reactions of bromobenzene and of 2-, 3- and 4-halogenopyridines with lithium wire inTHF solution yield the expected dimers, considerable dehalogenation also occurs, as monitored by¹³C-NMR spectroscopy. A pathway for the unusual formation of 4,4-bipyridyl from the 2-halogenopyridines is proposed. No dimers were detected from the reactions with 2-bromo-4-methylquinoline and 7-bromo-2,4-dimethylquinoline. The synthetic potential of their alternative facile sonochemical dehalogenation is propounded.

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Ultraschallunterstützte Kupplung von Aryl- und Hetarylhalogeniden in Gegenwart von Lithiumdraht. Die Bildung von dimeren und dehalogenierten Produkten

Zusammenfassung Obwohl die Ultraschall-Reaktionen von Brombenzol und 2-, 3- und 4-Halogenpyridinen mit Lithiumdraht inTHF die erwarteten Dimeren ergeben, tritt auch ein beträchtliches Ausmaß an Dehalogenierung ein. Es wird ein möglicher Mechanismus für die ungewöhnliche Bildung von 4,4-Bipyridyl aus 2-Halogenpyridin vorgeschlagen. Aus den Reaktionen von 2-Brom-4-methylchinolin und 7-Brom-2,4-dimethylchinolin resultierten keine dimeren Produkte. Das synthetische Potential der sonochemischen Dehalogenierung wird diskutiert.

     

Spectres RMN-13C DE β-Aminoalcools Derives DE L'Ephedrine ET De Leurs Oxazolidines

Abstract

The carbon-13 NMR spectra of β-aminoalcohols related to nor-and pseudonor-ephedrine (N-CH₃; N-C₂H₅; N-iC₃H₇; N-tC₄H₉) and the series of the corresponding oxazolidines from formaldehyde and benzaldehyde were obtained and dicussed. The configuration of the 3-alkyl-2, 5-diphenyl-4-methyloxazolidines was established.     

CRYSTALLIZATION SEGREGATION DSC STUDIES OF PP/PE COPOLYMERS

 The structural analysis of two PP/PE copolymer samples, I and 2, was conducted by using ¹³C-NMR, GPC and crystallization segregation DSC (CSDSC) techniques. A pure polypropylene sample was also used for comparison. It was found that the two copolymer samples are very close in composition (the ethylene mol content is 4.3% and 4.5%,respectively), stereoregularity (96% and 97%) and molecular weight (M_w, = 7.0 x 10⁴ and 7.3x10⁴; M_w/M_n = 5.0 and 6.1,respectively). While the CSDSC thermograms of the two samples are quite different from each other. Sample 1 shows a higher average melting temperature and a broader distribution of its thermogram. These phenomena were explained as an indication of a less uniform distribution of ethylene units along the PP chains for sample 1. It was noted that CSDSC is a very sensitive and convenient technique for structural studies of copolymers.     

1-Phenylamino-2-imidazoline und 1,2,5,6-Tetrahydro-1,2,4-triazine aus N-(2-Chloralkyl)-imidchloriden

1-Phenylamino-2-imidazolines3 and 1,2,5,6-tetrahydro-1,2,4-triazines4, 5 and6 are synthesized from N-(2-chloralkyl)-imidchlorides1 and phenylhydrazines. As intermediates are obtained the hydrochlorides of amidrazones2 which cyclise. The structure of the different heterocyclic systems are determined by¹H- and¹³C-NMR-spectroscopy.

     

Carbon-13 NMR Characterization of an O-Alkylated Derivative of the Theophylline Metabolite 1,3-Dimethyluric Acid

Abstract

The structure of the derivative formed during the reaction of 1,3-dimethyluric acid, the major metabolite of theophylline in humans, with iodopropane was elucidated. GC-MS analysis indicated the presence of a single dipropylated product even though three positional isomers are possible. The stability of the product was lower than anticipated since one of the alkyl groups added was readily removed by acid hydrolysis. Carbon-13 NMR proved to be the most useful technique for establishing the positions of alkylation. Assignment of carbon-13 resonances were consistent with placement of propyl groups on N-7 and on the oxygen at C-8. The structure of the product was assigned as 1,3-dimethyl-7-(1-propyl)-8-(1-propyloxy)xanthine. This O-alkylated structure is unusual since most heterocycles that can exist as lactim-lactam tautomers alkylate primarily on ring nitrogens.     

Adsorption and recovery issues of recombinant monoclonal antibodies in reversed‐phase liquid chromatography†

The poor recovery of large biomolecules is a well‐known issue in reversed‐phase liquid chromatography. Several papers have reported this problem, but the reasons behind this behavior are not yet fully understood. In the present study, state‐of‐the‐art reversed‐phase wide‐pore stationary phases were used to evaluate the adsorption of therapeutic monoclonal antibodies. These biomolecules possess molar mass of approximately 150 000 g/mol and isoelectric points between 6.6 and 9.3. Two types of stationary phases were tested, the Phenomenex Aeris Widepore (silica based), with 3.6 μm superficially porous particles, and the Waters Acquity BEH300 (ethylene‐bridged hybrid), with 1.7 μm fully porous particles. A systematic investigation was carried out using 11 immunoglobulin G1, G2, and G4 antibodies, namely, panitumumab, natalizumab, cetuximab, bevacizumab, trastuzumab, rituximab, palivizumab, belimumab, adalimumab, denosumab, and ofatumumab. All are approved by the Food and Drug Administration and the European Medicines Agency in various therapeutic indications and are considered as reference antibodies. Several test proteins, such as human serum albumin, transferrin, apoferritin, ovalbumin, and others, possessing a molar mass between 42 000 and 443 000 g/mol were also evaluated to draw reliable conclusions. The purpose of this study was to find a correlation between the adsorption of monoclonal antibodies and their physicochemical properties. Therefore, the impact of isoelectric point, molar mass, protein glycosylation, and hydrophobicity was investigated. The adsorption of intact antibodies on the stationary phase was significantly higher than that of proteins of similar size, isoelectric point, or hydrophobicity. The present study also demonstrates the unique behavior of monoclonal antibodies, contributing some unwanted and unpredictable strong secondary interactions.     

13C-NMR研究丁二烯-异戊二烯共聚合的竞聚率和共聚物的序列分布

 用¹³C-NMR方法研完了不同配料比的丁二烯-异戊二烯本体共聚和溶液共聚物的结构,定量计算出了共聚物二元组的浓度和数均序列长度,采用T(?)DO″S法计算出了本体共聚和溶液共聚的竞聚率,并证明各种共聚产物的序列分布都服从一级Markov统计模型。     

Carbon-13 Nuclear Magnetic Resonance Study of 5′-Substituted-5′-Oeoxyadenosine Derivatives

Abstract

A series of 5′-substituted-5′-deoxyadenosina derivatives, potential inhibitors of methyltransferases were synthesized and their carbon～13 nuclear magnetic resonance spectra investigated.     

Konformations-Gleichgewichte von 1,3-Oxathian-3-Imiden

Two 1,3-oxathiane-3-imides and 1,3-oxathiolane-3-p-chlorophenyl-imide have been prepared. The conformational equilibria of 1,3-oxathiane-3-oxide and of the two 1,3-oxathiane-3-imides have been determined by low temperature¹³C-NMR spectroscopy and compared to data obtained previously² for other cyclic sulfimides.

Herrn Prof. Dr.Karl Schlögl zum 60. Geburtstag gewidmet.     

On the tautomerism of 2,4-disubstituted 3,4,5,6-tetrahydrobenzo[h]quinazolines

Summary The tautomerism of the title compounds was investigated by¹H-,¹³C-NMR and UV spectroscopy. Compound5 was compared with respect to its spectra with those of appropriate model compounds1,3,4, and6. This gave evidence that5 predominates in the tautomeric from5A.

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Zur Tautomerie von 2,4-disubstituierten 3,4,5,6-Tetrahydrobenzo[h]chinazolinen

Zusammenfassung Die Tautomerie von 2,4-disubstituierten 3,4,5,6-Tetrahydrobenzo[h]chinazolinen wurde durch¹H-,¹³C-NMR- und UV-Spektroskopie untersucht. Der Vergleich der Spektren von5 und der Modellverbindungen1,3,4 und6 legt nahe, daß für5 das Tautomere5A dominiert.

     

New lipids from the soft corals of the Andaman Islands

Sphingolipids and glycolipids including previously unknown (2S,3S,4R)-1,3,4-trihydroxy-2-(2-(R)-hydroxyoctadecanoylamino)octadec-8E-ene, (2S,3R)-1,3-dihydroxy-2-octadecanoylamino-4E,8E-hexadecadiene, and (2-hydroxy-3-hexadecyloxypropyl)--L-fucopyranoside were isolated from soft corals collected on the shelf near the Andaman Islands (Indian Ocean). The structures of all compounds were established by spectroscopic methods and chemical analyses. The lipids possessed antibacterial activity against Bacillus subtilis, Bacillus pumilus, Escherichia coli, and Pseudomonas aeruginosa and antifungal activity against Aspergillus niger, Rhizopus oryzae, and Candida albicans.     

On the bromination of hypericin: The gymnochrome chromophores

Summary Stepwise electrophilic bromination of hypericin in pyridine as the solvent yields regioselectively 2,5-dibromohypericin, 2,5,9-tribromohypericin, and 2,5,9,12-tetrabromohypericin. The compounds were characterized by means of NMR-, UV-Vis-, and fluorescence-spectra, andpK _a andpK* _a measurements. These properties were compared with those of hypericin on the one hand and of the recently isolated gymnochromes on the other hand.

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Zur Bromierung des Hypericins: Die Gymnochrom-Chromophore

Zusammenfassung Schrittweise elektrophile Bromierung von Hypericin in Pyridin als Lösungsmittel liefert regioselektiv 2,5-Dibromhypericin, 2,5,9-Tribromhypericin und 2,5,9,12-Tetrabromhypericin. Diese Verbindungen wurden durch NMR-, UV-Vis- und Fluoreszenz-Spektrometrie sowie durchpK _a - undpk* _a -Messungen charakterisiert. Diese Eigenschaften wurden mit jenen des Hypericins und der kürzlich isolierten Gymnochrome verglichen.

     

Chemical Composition of the Essential Oils of <Emphasis Type="Italic">Bunium elegans</Emphasis> and <Emphasis Type="Italic">Bunium caroides</Emphasis>

Analyses of the essential oils of Bunium elegans (Fenzl) Freyn and B. caroides (Boiss.) Hausskn. ex Bornm., using GC, GC/MS, and¹³ C-NMR spectroscopy resulted in identification of their chemical constituents. The oils of both species contain mainly the sesquiterpene hydrocarbons germacrene-D and E-caryophyllene, which amounted to 24.1% and 38% for B. elegans and 22.1% and 26.6% for B. caroides respectively. The oil of B. caroides contained the monoterpenes α-pinene and Z-β-ocimene in 4.1 and 5.9% respectively, while traces of monoterpenes were detected for B. elegans. On the other hand, in B. caroides the phenylpropanoid derivatives asaricin (7.5%) and dillapiole (10.2%) were among the major constituents. __________ Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 335–336, July–August, 2005.