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NMR Study of Substituted Bicyclo[3.2.1]octanes
Author(s) -
Blunt John W.,
Burritt Andrew,
Coxon James M.,
Steel Peter J.
Publication year - 1996
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/(sici)1097-458x(199602)34:2<131::aid-omr846>3.0.co;2-t
Subject(s) - substituent , bromine , chemistry , bicyclic molecule , chemical shift , carbon 13 nmr , spectral line , stereochemistry , organic chemistry , physics , astronomy
The 1 H and 13 C NMR spectra of six bromo‐ and methoxybicyclo[3.2.1]octanes were completely assigned. An axial bromine substituent at C‐2 or C‐4 results in a 5 ppm upfield shift of C‐8 due to the gauche interaction. An equatorial bromine results in an upfield shift of similar magnitude on either C‐6 (or C‐7) due to a similar gauche interaction but has little effect on the chemical shift of C‐8. The 1,4‐ anti interaction of an axial bromine substituent on carbons C‐6 and/or C‐7 results in a small upfield shift (0.3 ppm) in parallel to the effect of an equatorial bromine on the chemical shift of C‐8. Similarly to the trend observed in bicyclo[2.2.1]heptanes, the substituent effects for 1,4‐ gauche and 1,4‐ anti interactions of the methoxy group are larger than for bromine.