Diazabenzenes. II. Synthesis, Photolysis and Mass Spectra of Some Tetraalkylpyrazines

1979 ◽  
Vol 32 (6) ◽  
pp. 1281 ◽  
Author(s):  
DJ Bell ◽  
IR Brown ◽  
R Cocks ◽  
RF Evans ◽  
GA Macfarlane ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
High Resolution ◽  
Sodium Borohydride ◽  
Mass Spectra ◽  
Ammonium Acetate ◽  
Zinc Dust ◽  
Deuterium Labelling ◽  
Complete Reduction ◽  
Pyrazine Ring ◽  
Resolution Mass

2,3,5,6-Tetramethyl-, tetraethyl- and tetraisopropyl-pyrazines were obtained by fusion of ammonium acetate with the appropriate acyloin or reduction of the α,α'-diketone dioxime with zinc dust and alkali. Photolysis of a cyclohexane solution of tetraisopropylpyrazine led inter alia to formation of bicyclohexyl. Photolysis of an aqueous solution of tetramethylpyrazine containing sodium borohydride caused complete reduction of the pyrazine ring to the hexahydro stage. The high-resolution mass spectra of these pyrazines are discussed and explained in the light of deuterium labelling and metastable defocusing information.

Diazabenzenes. I. Synthesis of some t-butylpyrazines and their N-oxides

1972 ◽  
Vol 25 (12) ◽  
pp. 2671 ◽  
Author(s):  
RF Evans ◽  
KN Mewett
Keyword(s):  
Steric Hindrance ◽  
Mass Spectra ◽  
Ammonium Acetate ◽  
Spectroscopic Properties ◽  
Iron Pentacarbonyl ◽  
Membered Ring ◽  
Low Resolution ◽  
Butyl Lithium ◽  
Pyrazine Ring ◽  
Resolution Mass

Steric hindrance prevented formation of tetra-t-butylpyrazine either when pivaloin was heated with ammonium acetate or when pivalil monooxime was reduced with zinc and alkali. Diminution of the steric hindrance of the t-butyl groups by masking them by incorporation into a seven-membered ring containing sulphur was of no avail. 2,5-Di-t- butylpyrazine resulted from the analogous reduction of t-butyl-glyoxal dioxime and could be converted into its N-oxide and N,N?-dioxide. t- Butyl-lithium reacted with the pyrazine and the mono-N-oxide to give a mixture of products including 2,3,5-tri-t-butylpyrazine whose spectroscopic properties suggested a buckling of the pyrazine ring. Benzonitrile and diphenylacetylene reacted independently in the presence of iron pentacarbonyl and gave, inter alia, 2,4,6-triphenyl- 1,3,5-triazine and hexaphenylbenzene respectively. ��� The most prominent features of the low resolution mass spectra of these pyrazines and some of their precursors are discussed and rationalized.

Exploring the Active Compounds of Traditional Mongolian Medicine Agsirga in Intervention of Novel Coronavirus (2019-nCoV) Based on HPLC-Q-Exactive-MS/MS and Molecular Docking Method

2020 ◽  
Author(s):  
Jie Cheng ◽  
Yuchen Tang ◽  
Baoquan Bao ◽  
Ping Zhang
Keyword(s):  
Mass Spectrometry ◽  
Molecular Docking ◽  
High Resolution ◽  
Mass Spectra ◽  
High Resolution Mass Spectrometry ◽  
Structural Formula ◽  
Active Compounds ◽  
High Resolution Mass ◽  
Q Exactive ◽  
Resolution Mass

<p><a></a><a></a><a></a><a><b>Objective</b></a>: To screen all compounds of Agsirga based on the HPLC-Q-Exactive high-resolution mass spectrometry and find potential inhibitors that can respond to 2019-nCoV from active compounds of Agsirga by molecular docking technology.</p> <p><b>Methods</b>: HPLC-Q-Exactive high-resolution mass spectrometry was adopted to identify the complex components of Mongolian medicine Agsirga, and separated by the high-resolution mass spectrometry Q-Exactive detector. Then the Orbitrap detector was used in tandem high-resolution mass spectrometry, and the related molecular and structural formula were found by using the chemsipider database and related literature, combined with precise molecular formulas (errors ≤ 5 × 10<sup>−6</sup>) , retention time, primary mass spectra, and secondary mass spectra information, The fragmentation regularities of mass spectra of these compounds were deduced. Taking ACE2 as the receptor and deduced compounds as the ligand, all of them were pretreated by discover studio, autodock and Chem3D. The molecular docking between the active ingredients and the target protein was studied by using AutoDock molecular docking software. The interaction between ligand and receptor is applied to provide a choice for screening anti-2019-nCoV drugs.</p> <p><b>Result</b>: Based on the fragmentation patterns of the reference compounds and consulting literature, a total of 96 major alkaloids and stilbenes were screened and identified in Agsirga by the HPLC-Q-Exactive-MS/MS method. Combining with molecular docking, a conclusion was got that there are potential active substances in Mongolian medicine Agsirga which can block the binding of ACE2 and 2019-nCoV at the molecular level.</p>

Mass-spectrometric studies. I. Benzo[b]thiophen, some alkyl and aryl derivatives, and the 1,1-dioxide and 2,3-dihydro-1,1-dioxide

1967 ◽  
Vol 20 (1) ◽  
pp. 103 ◽  
Author(s):  
QN Porter
Keyword(s):  
High Resolution ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
High Resolution Mass ◽  
Resolution Mass

The high-resolution mass spectra of benzo[b]thiophen, some alkyl and aryl derivatives, and the sulphone and 2,3-dihydrosulphone have been obtained; compositions of all significant ions in the spectra have been determined. Fragmentations of the unoxidized compounds are dominated by losses of C2H2 and CS units, while the sulphones undergo initial isomerization to cyclic sulphinates followed by expulsion of SO and fragments containing a C-O bond. Structures have been suggested for most of the ions observed.

Computer Interpretation of High Resolution Mass Spectra*

Nature ◽  
1966 ◽  
Vol 212 (5064) ◽  
pp. 784-787 ◽  
Author(s):  
M. BARBER ◽  
P. POWERS ◽  
M. J. WALLINGTON ◽  
W. A. WOLSTENHOLME
Keyword(s):  
High Resolution ◽  
Mass Spectra ◽  
Computer Interpretation ◽  
High Resolution Mass ◽  
Resolution Mass

scholarly journals High-resolution serum proteomic features for ovarian cancer detection.

2004 ◽  
Vol 11 (2) ◽  
pp. 163-178 ◽  
Author(s):  
T P Conrads ◽  
V A Fusaro ◽  
S Ross ◽  
D Johann ◽  
V Rajapakse ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
High Resolution ◽  
Sensitivity And Specificity ◽  
Mass Spectra ◽  
Spectral Feature ◽  
Low Resolution ◽  
Mass Spectral ◽  
High Resolution Mass ◽  
Process Error ◽  
Resolution Mass

Serum proteomic pattern diagnostics is an emerging paradigm employing low-resolution mass spectrometry (MS) to generate a set of biomarker classifiers. In the present study, we utilized a well-controlled ovarian cancer serum study set to compare the sensitivity and specificity of serum proteomic diagnostic patterns acquired using a high-resolution versus a low-resolution MS platform. In blinded testing sets, the high-resolution mass spectral data contained multiple diagnostic signatures that were superior to the low-resolution spectra in terms of sensitivity and specificity (P<0.00001) throughout the range of modeling conditions. Four mass spectral feature set patterns acquired from data obtained exclusively with the high-resolution mass spectrometer were 100% specific and sensitive in their diagnosis of serum samples as being acquired from either unaffected patients or those suffering from ovarian cancer. Important to the future of proteomic pattern diagnostics is the ability to recognize inferior spectra statistically, so that those resulting from a specific process error are recognized prior to their potentially incorrect (and damaging) diagnosis. To meet this need, we have developed a series of quality-assurance and in-process control procedures to (a) globally evaluate sources of sample variability, (b) identify outlying mass spectra, and (c) develop quality-control release specifications. From these quality-assurance and control (QA/QC) specifications, we identified 32 mass spectra out of the total 248 that showed statistically significant differences from the norm. Hence, 216 of the initial 248 high-resolution mass spectra were determined to be of high quality and were remodeled by pattern-recognition analysis. Again, we obtained four mass spectral feature set patterns that also exhibited 100% sensitivity and specificity in blinded validation tests (68/68 cancer: including 18/18 stage I, and 43/43 healthy). We conclude that (a) the use of high-resolution MS yields superior classification patterns as compared with those obtained with lower resolution instrumentation; (b) although the process error that we discovered did not have a deleterious impact on the present results obtained from proteomic pattern analysis, the major source of spectral variability emanated from mass spectral acquisition, and not bias at the clinical collection site; (c) this variability can be reduced and monitored through the use of QA/QC statistical procedures; (d) multiple and distinct proteomic patterns, comprising low molecular weight biomarkers, detected by high-resolution MS achieve accuracies surpassing individual biomarkers, warranting validation in a large clinical study.

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