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Type: Artigo de periódico
Title: A Carbon-13 Nmr Study Of New 4-substituted Neostigmine Methyl Sulphates: Correlations Of Substituent-induced Chemical Shifts With Substituent Parameters
Author: Rittner R.
Barbarini J.E.
Abstract: The Carbon-13 NMR spectra of six new neostigimine derivatives, the 4-substituted-3-[{N,N-dimethylamino)carbonyl}oxy]-N′,N′,N′-tri methylbenzen-amminium methyl sulphates (4-substituted neostigmine methyl sulphates), and of the parent compound were recorded, and unequivocal chemical shift assignments through the use of HETCOR and COLOC sequences were performed. Large intramolecular interaction chemical shifts (ICS) were observed for carbon C-3 (-8.3 to +3.1 ppm), attachment site of the OC(O)N(CH3)2 group, and moderate ICS values (-3.3 to +3.5 ppm) for the remaining ring carbons, similarly to the values which were found for C-1 (-9.3 to +3.4 ppm) and for C-2 to C-6 (-3.0 to +3.8 ppm) of the corresponding 2-substituted-5-N′,N′-dimethylaminophenyl-N,N-dimethylcarbamates. Correlation analyses for the substituent-induced chemical shifts (SCS) with several sets of substituent parameters were carried out, through SSP, DSP and DSP-NLR treatments, as well as through multiple regression analysis. Good correlations were found for all ring carbons (r>0.97) and for the carbonyl carbon (r 0.9797). Resonance contribution is predominant for C-1 and C-2, while the electronegativity or inductive parameter is significant or the prevailing component for all ring carbons. Negative r values were found for several correlations (reverse substituent effect).
Rights: fechado
Identifier DOI: 
Date Issue: 2000
Appears in Collections:Unicamp - Artigos e Outros Documentos

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