Azaborolyl-Komplexe, 27 / Azaborolyl Complexes, 27

1992 ◽  
Vol 47 (5) ◽  
pp. 635-639 ◽  
Author(s):  
Günter Schmid ◽  
Wolfgang Meyer-Zaika
Keyword(s):  
Mass Spectrometry ◽  
Benzene Solution ◽  
Stable Complex ◽  
Intramolecular Rearrangement ◽  
The Novel ◽  
Intramolecular Coordination ◽  
Tert Butyl ◽  
Nmr Data ◽  
Stereoselective Reactions ◽  
Ab Ring

Alkenyl substituted 1H-1,2-azaborolyl (Ab) complexes are promising candidates for stereoselective reactions, due to the chirality of the AbM moiety and the intramolecular coordination of the alkenyl group to the metal atom. The synthesis of [1-tert-butyl-2-methy1-3-(4-penten- l -y1)-η5-1H-1,2-azaborolyl]-bis(triphenylphosphine)rhodium (3) is achieved by the reaction of AbLi (2) [from AbH (1)] with (Ph3P)3RhCl. In benzene solution one PPh3 ligand of 3 is substituted by the C=C group of the pentenyl substituent. Simultaneously the η5-coordination of the Ab ring changes to an allylic η3-coordination forming 4. Steric reasons seem to be responsible for this intramolecular rearrangement. The shorter 2-propen-1-yl substituent is unable to act in the same way and therefore only forms the stable complex [1-tert-butyl-2-methyl-3-(2-propen- l -yl)-η5-1H-1,2-azaborolyl]-bis(triphenylphosphine)rhodium (7). Mass spectrometry, 1H, 11B and 31P NMR data were used to characterize the novel complexes.

Synthesis of metal-free tetraazaisobacteriochlorin and via template condensation of phthalogenes

2020 ◽  
Vol 24 (05n07) ◽  
pp. 878-886
Author(s):  
Semyon V. Dudkin ◽  
Takahiro Kawata ◽  
Svetlana A. Belova ◽  
Yusuke Okada ◽  
Nagao Kobayashi
Keyword(s):  
Mass Spectrometry ◽  
Quantum Chemical ◽  
2D Nmr ◽  
Metal Free ◽  
Tert Butyl ◽  
H Nmr ◽  
Nmr Data ◽  
Template Condensation ◽  
Td Dft ◽  
Low Symmetry

The indium(III) complexes of (4-(tert-butyl)phenyl)-substituted tetraazaisobacteriochlorin (TAiBC) and tetraazachlorin (TAC) were synthesized by direct template condensation of bis(4-(tert-butyl)phenyl)fumaronitrile and tetramethylsuccinonitrile using indium(III) ion as a matrix. The corresponding metal-free tetraazaisobacteriochlorin and tetraazachlorin were obtained by demetallation of their indium(III) complexes. These metal-free complexes were characterized using elemental analysis, mass-spectrometry, 1H and [Formula: see text]C{1H}NMR spectroscopy, UV-vis and MCD spectroscopy as well as DFT and TD-DFT calculations. Due to the low symmetry of the molecules, the NMR data were complex, but could be assigned by collecting 1D- and 2D NMR data and comparing with the results of quantum chemical calculations. From the position of the pyrrole proton signal (6.78 ppm), it was found that the diatropic current of TAiBC is much weaker than that of TAC, and plausibly the weakest among porphyrinoids so far reported. Absorption and MCD spectra were reasonably interpreted using the calculated absorption spectra.

Synthetic application of α-hydroxydiazene systems. II. Uncatalyzed and phenol catalyzed radical chain hydro-tert-butylation of unsaturated compounds with tert-butylazodiphenylcarbinol

1976 ◽  
Vol 54 (9) ◽  
pp. 1345-1348 ◽  
Author(s):  
Dominic W. K. Yeung ◽  
John Warkentin
Keyword(s):  
Benzene Solution ◽  
Chain Process ◽  
The Novel ◽  
Radical Chain ◽  
Tert Butyl ◽  
Radical Adduct ◽  
Butyl Radical ◽  
A Chain ◽  
Radical Traps ◽  
Synthetic Application

tert-Butylazodiphenylcarbinol 1 decomposes in benzene solution by a chain mechanism involving tert-butyl radicals. Many olefinic compounds and azobenzene act as radical traps and are hydro-tert-butylated by 1. The regiochemistry of hydro-tert-butylation of unsymmetric alkenes is that expected for a mechanism which involves addition of tert-butyl radical so as to form the most stable radical adduct, which subsequently abstracts hydrogen from 1.In some cases phenol acts as a catalyst for the hydroalkylation process. The novel catalytic effect of phenol in a radical chain process is attributed to the favourable thermochemistry for induced, concerted decomposition of 1 by radical attack at hydroxyl hydrogen.

scholarly journals Two New Phomaligols from the Marine-Derived Fungus Aspergillus flocculosus and Their Anti-Neuroinflammatory Activity in BV-2 Microglial Cells

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 65
Author(s):  
Byeoung-Kyu Choi ◽  
Duk-Yeon Cho ◽  
Dong-Kug Choi ◽  
Phan Thi Hoai Trinh ◽  
Hee Jae Shin
Keyword(s):  
Nitric Oxide ◽  
Mass Spectrometry ◽  
Optical Rotation ◽  
Chemical Oxidation ◽  
Culture Broth ◽  
Membered Ring ◽  
Microglial Cells ◽  
No Production ◽  
Nmr Data ◽  
Ic50 Value

Two new phomaligols, deketo-phomaligol A (1) and phomaligol E (2), together with six known compounds (3–8) were isolated from the culture broth of the marine-derived fungus Aspergillus flocculosus. Compound 1 was first isolated as a phomaligol derivative possessing a five-membered ring. The structures and absolute configurations of the new phomaligols were determined by detailed analyses of mass spectrometry (MS), nuclear magnetic resonance (NMR) data, optical rotation values and electronic circular dichroism (ECD). In addition, the absolute configurations of the known compounds 3 and 4 were confirmed by chemical oxidation and comparison of optical rotation values. Isolated compounds at a concentration of 100 μM were screened for inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-induced BV-2 microglial cells. Among the compounds, 4 showed moderate anti-neuroinflammatory effects with an IC50 value of 56.6 μM by suppressing the production of pro-inflammatory mediators in activated microglial cells without cytotoxicity.

scholarly journals Ambient-Temperature Synthesis of (E)-N-(3-(tert-Butyl)-1-methyl-1H-pyrazol-5-yl)-1-(pyridin-2-yl)methanimine

Molbank ◽  
10.3390/m1250 ◽  
2021 ◽  
Vol 2021 (3) ◽  
pp. M1250
Author(s):  
Diana Becerra ◽  
Justo Cobo ◽  
Juan-Carlos Castillo
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Ambient Temperature ◽  
Magnesium Sulfate ◽  
Elemental Analysis ◽  
Condensation Reaction ◽  
2D Nmr ◽  
2D Nmr Spectroscopy ◽  
Temperature Synthesis ◽  
Tert Butyl

We report the ambient-temperature synthesis of novel (E)-N-(3-(tert-butyl)-1-methyl-1H-pyrazol-5-yl)-1-(pyridin-2-yl)methanamine 3 in 81% yield by a condensation reaction between 3-(tert-butyl)-1-methyl-1H-pyrazol-5-amine 1 and 2-pyridinecarboxaldehyde 2 in methanol using magnesium sulfate as a drying agent. The N-pyrazolyl imine 3 was full characterized by IR, 1D, and 2D NMR spectroscopy, mass spectrometry, and elemental analysis.

Bleispezies PbX und PbX2 als Brückenliganden in übergangsmetallorganisch geschützten Koordinationsverbindungen/ Leadspecies PbX and PbX2 as Bridging Ligands in Organometallic Protected Coordination Compounds

2002 ◽  
Vol 57 (1) ◽  
pp. 25-42 ◽  
Author(s):  
Peter Rutsch ◽  
Gottfried Huttner
Keyword(s):  
Coordination Compounds ◽  
Dynamic Behaviour ◽  
Disodium Salt ◽  
3D Nmr ◽  
Spectroscopic Techniques ◽  
The Novel ◽  
Bridging Ligands ◽  
X Ray ◽  
Nmr Data ◽  
First Time

The disodium salt Na2[{(CO)5Cr}2Pb(NO3)2], Na2·1, which contains a lead center in a (4+2) coordination mode, reacts with tetraphenylphosphonium halides [Ph4P]X to give the tetrahedral compounds [Ph4P]2[{(CO)5Cr}2PbX2] (X = Cl: 2a; X = Br: 2b; X = I: 2c). Substitution of the nitrate groups of Na2·1 by alcoxides leads to binuclear compounds of the type [{(CO)5Crg2Pb(μ2-OR)2Pb{Cr(CO)5}2]2- (R = Et: 3a; R = n -Pr: 3b; R = i-Pr: 3c; R = Allyl: 3d). NMR experiments show that these dimeric compounds are in equilibrium with the monomeric species [{(CO)5Cr}2PbR]- .Trialkylphosphanes react with Na2·1 to give the neutral phosphane complexes [{(CO)5Cr}2Pb(PR3)2] (R=Me: 4a; R=Et: 4b; R = n-Bu: 4c), which show dynamic behaviour in solution. All of the novel compounds have been characterized by X-ray analysis, as well as by the usual analytic and spectroscopic techniques. 207Pb-NMR data of Cr(CO)5- bound lead species are reported for the first time.

Relationship between plasma and salivary melatonin and cortisol investigated by LC-MS/MS

2017 ◽  
Vol 55 (9) ◽  
Author(s):  
Martijn van Faassen ◽  
Rainer Bischoff ◽  
Ido P. Kema
Keyword(s):  
Mass Spectrometry ◽  
Equilibrium Dialysis ◽  
Added Value ◽  
The Novel ◽  
Plasma Melatonin ◽  
Disease States ◽  
Validation Criteria ◽  
Significant Difference ◽  
Salivary Melatonin ◽  
Free Plasma

AbstractBackground:Disturbance of the circadian rhythm has been associated with disease states, such as metabolic disorders, depression and cancer. Quantification of the circadian markers such as melatonin and cortisol critically depend on reliable and reproducible analytical methods. Previously, melatonin and cortisol were primarily analyzed separately, mainly using immunoassays.Methods:Here we describe the validation and application of a high-throughput liquid chromatography in combination with mass spectrometry (LC-MS/MS) method for the combined analysis of melatonin and cortisol in plasma and saliva. The LC-MS/MS method was validated according to international validation guidelines. We used this method to analyze total plasma, free plasma (as obtained by equilibrium dialysis) and saliva melatonin and cortisol in healthy adults.Results:Validation results for plasma and saliva melatonin and cortisol were well within the international validation criteria. We observed no difference between saliva collected by passive drooling or Salivette. Moreover, we noted a significant difference in saliva vs. free plasma melatonin. We observed on average 36% (95% CI: 4%–60%) higher salivary melatonin levels in comparison to free plasma melatonin, suggestive of local production of melatonin in the salivary glands.Conclusions:The novel outcome of this study is probably due to the high precision of our LC-MS/MS assay. These outcomes illustrate the added value of accurate and sensitive mass spectrometry based methods for the quantification of neuroendocrine biomarkers.

Trichlorsilylierung sperriger Dialkylchlorphosphane und Tetraalkyldiphosphane mit Hexachlordisilan / Trichlorosilylation of Bulky Dialkylchlorophosphanes and Tetraalkyldiphosphanes with Hexachlorodisilane

1991 ◽  
Vol 46 (12) ◽  
pp. 1609-1612 ◽  
Author(s):  
Reiner Martens ◽  
Wolf-Walther du Mont ◽  
Lutz Lange
Keyword(s):  
Silver Bromide ◽  
Tert Butyl ◽  
Nmr Data

Chlorodiisopropylphosphane reacts with hexachlorodisilane to give diisopropyl(trichlorosilyl)phosphane which reacts with the educt chlorophosphane to produce tetraisopropyldiphosphane. Tetraisopropyldiphosphane reacts with hexachlorodisilane to provide diisopropyl(trichlorosilyl)phosphane. With di-tert-butylchlorophosphane and tetra-tert-butyldiphosphane, the corresponding reactions leading to di-tert-butyl(trichlorosilyl)phosphane are much slower; while the product does not react further with di-tert-butylchlorophosphane, it does with chlorodiisopropylphosphane. A stable 1:1 complex is formed from di-tert-butyl(trichlorosilylphosphane) with silver bromide. Products are characterized on the basis of analytical and 1H, 13C, 29Si and 31P NMR data.

scholarly journals Qualitative analysis of 7- and 8-hydroxyzolpidem and discovery of novel zolpidem metabolites in postmortem urine using liquid chromatography–tandem mass spectrometry

2022 ◽  
Author(s):  
Koji Yamaguchi ◽  
Hajime Miyaguchi ◽  
Youkichi Ohno ◽  
Yoshimasa Kanawaku
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Pyridine Ring ◽  
Multiple Reaction Monitoring ◽  
Fragmentation Pattern ◽  
The Novel ◽  
Flight Mass Spectrometry ◽  
Urine Extract ◽  
Liquid Chromatography Tandem Mass ◽  
Characteristic Fragmentation

Abstract Purpose Zolpidem (ZOL) is a hypnotic sometimes used in drug-facilitated crimes. Understanding ZOL metabolism is important for proving ZOL intake. In this study, we synthesized standards of hydroxyzolpidems with a hydroxy group attached to the pyridine ring and analyzed them to prove their presence in postmortem urine. We also searched for novel ZOL metabolites in the urine sample using liquid chromatography–triple quadrupole mass spectrometry (LC-QqQMS) and liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-QqTOFMS). Methods 7- and 8-Hydroxyzolpidem (7OHZ and 8OHZ, respectively) were synthesized and analyzed using LC-QqQMS. Retention times were compared between the synthetic standards and extracts of postmortem urine. To search for novel ZOL metabolites, first, the urine extract was analyzed with data-dependent acquisition, and the peaks showing the characteristic fragmentation pattern of ZOL were selected. Second, product ion spectra of these peaks at various collision energies were acquired and fragments that could be used for multiple reaction monitoring (MRM) were chosen. Finally, MRM parameters were optimized using the urine extract. These peaks were also analyzed using LC-QqTOFMS. Results The presence of 7OHZ and 8OHZ in urine was confirmed. The highest peak among hydroxyzolpidems was assigned to 7OHZ. The novel metabolites found were zolpidem dihydrodiol and its glucuronides, cysteine adducts of ZOL and dihydro(hydroxy)zolpidem, and glucuronides of hydroxyzolpidems. Conclusions The presence of novel metabolites revealed new metabolic pathways, which involve formation of an epoxide on the pyridine ring as an intermediate.

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