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A carbon‐13 NMR study of some alkyl‐substituted indenes. An experimental study of the baker‐nathan order of hyperconjugation in the neutral ground state
Author(s) -
Edlund Ulf
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.1270111009
Subject(s) - substituent , hyperconjugation , chemistry , alkyl , conjugated system , isopropyl , carbon 13 nmr , benzene , ground state , stereochemistry , medicinal chemistry , photochemistry , organic chemistry , molecule , polymer , physics , atomic physics
Carbon‐13 NMR spectra of several alkyl‐substituted indenes have been assigned and analysed. For structures having an alkyl substituent in the C‐2 position an increased shielding was observed for the remote conjugated positions C‐4 and C‐6, an alternating trend similar to that found for the 2‐cycloaminoindenes. The hyperconjugative behaviour was slightly more pronounced for the methyl group compared with an isopropyl or tert ‐butyl substituent, a fact which supports a model where CH σ–π interactions are more efficient than those involving CC bonds.