Nortricyclanols rearrangement

Whereas exo-norbornene oxide rearranges to nortricyclanol on treatment with strong base through transannular C-H insertion (Scheme 5.11), endo-norbornene oxide 64 gives norcamphor 65 as the major product (Scheme 5.14) [15, 22]. This product arises from 1,2-hydrogen migration very little transannular rearrangement is observed. These two reaction pathways are often found to be in competition with one another, and subtle differences in substrate structure, and even in the base employed, can have a profound influence on product distribution. 

Remote double bonds often participate in epoxide openings, sometimes with extensive skeletal changes. ejco-Norbomadiene oxide (15 equation 6) provides an interesting example. Meinwald et alP found that this very acid-sensitive material rearranged simply on standing to give the endo-aldehyde (17), presumably via the intermediate nortricyclanol ion (16). 

D. M. Hodgson, R. Wisedale, Enantioselective rearrangement of exo-norbornene oxide to nortricyclanol, Tetrahedron Asymm. 7 (1996) 1275. 

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