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Carbon‐13 nuclear magnetic resonance spectroscopy of methyl‐substituted piperidines and their hydrochloride salts
Author(s) -
Beguin Claude G.,
Deschamps MarieNoëlle,
Boubel Véronique,
Delpuech JeanJacques
Publication year - 1978
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270110811
Subject(s) - chemistry , substituent , cyclohexanes , protonation , piperidine , chemical shift , steric effects , ring (chemistry) , hydrochloride , methyl group , nuclear magnetic resonance spectroscopy , medicinal chemistry , nitrogen atom , resonance (particle physics) , nitrogen , spectroscopy , stereochemistry , organic chemistry , alkyl , ion , physics , particle physics , quantum mechanics
Carbon‐13 chemical shifts and 1 J (CH) coupling constants of piperidine, 4‐ t ‐butylpiperidine, five C‐methyl substituted piperidines and of the corresponding N‐methyl compounds have been measured. These NMR parameters have also been determined for the fourteen corresponding hydrochlorides. The N‐methyl‐C‐methyl piperidinium salts showed two stereoisomers on the positive nitrogen atom. The effect of protonation is discussed in relation to charge and steric effects and the methyl substituent effects are compared with those of methyl‐substituted cyclohexanes. Deviations from the general tendencies in the series are correlated with changes in ring conformations around the highly crowded substituted carbons.