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A 1H and 13C NMR conformational study of methyl-substituted isochromanes

✍ Scribed by K. Pihlaja; J. Mattinen; E. Kleinpeter; R. Meusinger; Ch. Duscheck; R. Borsdorf

Publisher: John Wiley and Sons
Year: 1985
Tongue: English
Weight: 426 KB
Volume: 23
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1260230915

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✦ Synopsis

The 'H and the noise-decoupled =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 ' I 3 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 -C chemical shifts of the oxme ring carbons were derived and compared with those of l,3-dioxanes. Their usefulness in conformational analysis is demonstrated for 1-methylipochromane.

' r-I ,t-3.~4/r-1.~-3.t4.

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