NMR Study of Substituted Bicyclo[3.2.1]octanes

✍ Scribed by John W. Blunt; Andrew Burritt; James M. Coxon; Peter J. Steel

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 455 KB
• Volume: 34
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/(sici)1097-458x(199602)34:2<131::aid-omr846>3.0.co;2-t

✦ Synopsis

The 'H and I3C 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-anfi 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[ 2.2.11 heptanes, the substituent effects for 1,4-guuche and 1,6anti interactions of the methoxy group are larger than for bromine.