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Quaternization of pyrido[2,3‐ b ]pyrazines: 1 H and 13 C NMR Study
Author(s) -
Chupakhin O. N.,
Charushin V. N.,
Chernyshev A. I.,
Esipov S. E.
Publication year - 1985
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260230607
Subject(s) - chemistry , pyrazine , methyl iodide , ring (chemistry) , pyridine , iodide , alkylation , chemical shift , medicinal chemistry , carbon 13 nmr , nuclear magnetic resonance spectroscopy , ethyl iodide , proton nmr , stereochemistry , organic chemistry , catalysis
The structure of N ‐methylpyrido[2,3‐ b ]pyrazinium salts has been examined by 1 H and 13 C NMR. 6‐Dimethylamino‐ and 6‐morpholino‐pyrido[2,3‐ b ]pyrazines were shown to undergo quaternization by methyl iodide at N‐4 of the pyrazine ring, whereas the pyridine ring N‐5 was the N ‐alkylation site in the reaction of unsubstituted pyrido[2,3‐ b ]pyrazine with methyl iodide under the same conditions. The effects of quaternization on the 1 H and 13 C chemical shifts and the n J (CH) values are discussed.