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A 1 H and 13 C NMR conformational study of methyl‐substituted isochromanes
Author(s) -
Pihlaja K.,
Mattinen J.,
Kleinpeter E.,
Meusinger R.,
Duscheck Ch.,
Borsdorf R.
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.1260230915
Subject(s) - chemistry , vicinal , conformational isomerism , ring (chemistry) , substituent , moiety , chemical shift , stereochemistry , cyclohexane conformation , nmr spectra database , methyl group , crystallography , carbon 13 nmr , computational chemistry , spectral line , molecule , alkyl , organic chemistry , hydrogen bond , physics , astronomy
The 1 H and the noise‐decoupled 13 C NMR spectra of isochromane and 13 of its methyl‐substituted derivatives were recorded and analysed. The collected data were used to assign the configurations and to determine the position of the conformational equilibria based on the vicinal 1 H coupling constants of the aliphatic moiety of the ring system. In some cases the substitution site‐dependent conformational energies of the methyl substituents were also used to estimate the conformer ratios. The primary and some vicinal methyl substituent effects on the 13 C chemical shifts of the oxane ring carbons were derived and compared with those of 1,3‐dioxanes. Their usefulness in conformational analysis is demonstrated for 1‐methylisochromane.