Substituent effects on the chemical shifts of the bridge protons of benzonorbornenes
- 1 June 1967
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Chemistry
- Vol. 45 (11) , 1185-1193
- https://doi.org/10.1139/v67-197
Abstract
The substituent effects on the chemical shifts of the C9 bridge protons in a series of 6-substituted benzonorbornenes and benzonorbornadienes, and on those of the C2 protons in 5-substituted 2-indanols, were investigated. They were linearly correlated with the modified Hammett relationship τR − τH = ρ (σm + σp)/2. The ρ values obtained from the anti-C9 protons in the bornenes and bornadienes were slightly but significantly larger than those from the corresponding syn protons, whereas no significant difference was observed between the ρ values obtained from syn-9-benzonorbornenols and the indanols. The larger ρanti values were explained in terms of a stereospecific electronic interaction between the π-electron system of the benzene ring and the orbital system of the bridge carbon. In addition, it was shown that the above modified Hammett relationship gives generally a good agreement with the substituent effects on the aliphatic constituents of benzocyclenes and analogous compounds.Keywords
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