Bicyclo hepten cations

CIDNP effects observed for norcarene [147, 178] supported a radical cation, 87 +, which spin and charge are delocalized between the olefinic group and the Walsh orbital of the (more highly substituted) internal cyclopropane bond. The bicyclo-heptene system, 87 +, appears to be more flexible than 86 + either the internal or the lateral cyclopropane bond can align with the alkene p-orbitals. Delocalization of spin and charge into the more highly substituted bond is preferred. 

The behavior of members of the bicyclo[2.2.1]heptene family is also different from that of other common 1,2-disubstituted alkenes.230 The parent bicy-clo[2.2.1]heptene gives bicyclo[2.2.1]heptane in only 3.5% yield when it is treated with Et3SiH/TFA. The major product is reported to be a 2-bicyclo[2.2.1]heptyl trifluoroacetate of unspecified configuration (Eq. 70).230 The carbocation intermediate is presumably the 2-norbornyl cation. Addition of small amounts of boron trifluoride etherate to the reaction mixture causes the yield of hydrocarbon product to rise to 22% after a reaction time of 24 hours at room temperature. Further... 

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