89378-45-0Relevant academic research and scientific papers
2-Bicycloheptyl and 7-Norbornyl Cations
Kirmse, Wolfgang,Streu, Joachim
, p. 4187 - 4194 (2007/10/02)
The structure and reactivity of 2-bicycloheptyl and 7-norbornyl cations have been probed with the aid of optically active, deuterium-labeled, and methyl-substituted precursors.Bicycloheptyl-6,7-d2 and 6-methyl- and 7-methylbicycloheptyl substrates rearranged with > 98percent inversion at the migration origin to give anti-7-norbornyl products.Optically active 2-methylbicycloheptyl substrates afforded 1-methyl-7-norbornanol of > 98percent ee.Anti-syn leakage is characteristic of 7-norbornyl substrates and may be due to kΔ,kc competition.Several carbocations have been shown to undergo "same-side bridge-flipping" (2a2b), leading to partial racemization of the parent system and to structural isomerization of others.Bridge-flipping has not been observed with 2-methylbicyclo heptyl substrates, owing to stabilization of the carbocation by Me.The product distributions cannot be rationalized in terms of open (classical) ions.Bridged (nonclassical) intermediates provide an internally consistent interpretation of our data.
