13C Chemical Shifts of Highly Substituted Bicyclo[2.2.1]heptanes

The 13 C chemical shifts have been determined for a series of highly substituted norbornanes. A comparison of the observed values with the expected chemical shifts, determined as described by Lippmaa, establishes that 13 C shifts may be predicted reasonably accurately even in highly substituted norbornyl systems. Since substituted norbornanes definitely exist in synchro or contra twist forms as shown by Altona, the results show that Lippmaa's …