Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data

Investigations were carried out applying NMR spectroscopy for the unambiguous determination of the position of the N-oxide function in a set of 2-substituted pyrazine N-oxides synthesized in our group. Applying chemometric techniques of multivariate analysis to the 13C NMR chemical shifts data set,...

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Autores principales: Butler, M., Cabrera, G.M.
Formato: JOUR
Materias:
13C
Chemometric analysis
NMR
Position of N-oxide
Pyrazine N-oxides
Structure elucidation
<sup>13</sup>C
N-Oxides
Atoms
Chemical shift
Nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy
Carbon
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00222860_v1043_n_p37_Butler
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00222860_v1043_n_p37_Butler2023-10-03T14:30:30Z Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data Butler, M. Cabrera, G.M. 13C Chemometric analysis NMR Position of N-oxide Pyrazine N-oxides Structure elucidation <sup>13</sup>C Chemometric analysis N-Oxides Position of N-oxide Structure elucidation Atoms Chemical shift Nuclear magnetic resonance Nuclear magnetic resonance spectroscopy Carbon Investigations were carried out applying NMR spectroscopy for the unambiguous determination of the position of the N-oxide function in a set of 2-substituted pyrazine N-oxides synthesized in our group. Applying chemometric techniques of multivariate analysis to the 13C NMR chemical shifts data set, useful relationships for identifying the position of the N-oxide group relative to the substituent were unraveled. The relationships obtained were rationalized in terms of the molecular structures and refined. As a result, an index of N-oxidation (INOx) was defined, computed simply contrasting the average 13C NMR chemical shifts of each pair of carbon atoms bonded to a nitrogen atom. The effect of the substituent was included through a factor x (subscript of INO) close to unity, multiplying the average containing the substituted carbon atom. The approach was successful in recognizing the position of the N-oxide in all the cases studied, as revealed by the sign of INOx (positive for 1-N-oxides and negative for 4-N-oxides). The scope of the methodology was further tested using the 13C NMR chemical shifts of disubstituted pyrazine N-oxides from the literature data. © 2013 Elsevier B.V. All rights reserved. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00222860_v1043_n_p37_Butler
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic 13C
Chemometric analysis
NMR
Position of N-oxide
Pyrazine N-oxides
Structure elucidation
<sup>13</sup>C
Chemometric analysis
N-Oxides
Position of N-oxide
Structure elucidation
Atoms
Chemical shift
Nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy
Carbon
spellingShingle 13C
Chemometric analysis
NMR
Position of N-oxide
Pyrazine N-oxides
Structure elucidation
<sup>13</sup>C
Chemometric analysis
N-Oxides
Position of N-oxide
Structure elucidation
Atoms
Chemical shift
Nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy
Carbon
Butler, M.
Cabrera, G.M.
Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data
topic_facet 13C
Chemometric analysis
NMR
Position of N-oxide
Pyrazine N-oxides
Structure elucidation
<sup>13</sup>C
Chemometric analysis
N-Oxides
Position of N-oxide
Structure elucidation
Atoms
Chemical shift
Nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy
Carbon
description Investigations were carried out applying NMR spectroscopy for the unambiguous determination of the position of the N-oxide function in a set of 2-substituted pyrazine N-oxides synthesized in our group. Applying chemometric techniques of multivariate analysis to the 13C NMR chemical shifts data set, useful relationships for identifying the position of the N-oxide group relative to the substituent were unraveled. The relationships obtained were rationalized in terms of the molecular structures and refined. As a result, an index of N-oxidation (INOx) was defined, computed simply contrasting the average 13C NMR chemical shifts of each pair of carbon atoms bonded to a nitrogen atom. The effect of the substituent was included through a factor x (subscript of INO) close to unity, multiplying the average containing the substituted carbon atom. The approach was successful in recognizing the position of the N-oxide in all the cases studied, as revealed by the sign of INOx (positive for 1-N-oxides and negative for 4-N-oxides). The scope of the methodology was further tested using the 13C NMR chemical shifts of disubstituted pyrazine N-oxides from the literature data. © 2013 Elsevier B.V. All rights reserved.
format JOUR
author Butler, M.
Cabrera, G.M.
author_facet Butler, M.
Cabrera, G.M.
author_sort Butler, M.
title Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data
title_short Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data
title_full Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data
title_fullStr Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data
title_full_unstemmed Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data
title_sort determination of the position of the n-o function in substituted pyrazine n-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data
url http://hdl.handle.net/20.500.12110/paper_00222860_v1043_n_p37_Butler
work_keys_str_mv AT butlerm determinationofthepositionofthenofunctioninsubstitutedpyrazinenoxidesbychemometricanalysisofcarbon13nuclearmagneticresonancedata
AT cabreragm determinationofthepositionofthenofunctioninsubstitutedpyrazinenoxidesbychemometricanalysisofcarbon13nuclearmagneticresonancedata
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