Selective hydrogenation of the vinyl group in 5-vinyl-2-norbornene

Reduce the exocyclic vinyl group to ethyl while keeping the endocyclic norbornene double bond intact.
The strained endocyclic C=C of norbornene is usually the more reactive of the two toward catalytic hydrogenation, so standard catalysts affect the endocyclic double bond first or both at once. The selectivity needs to be inverted.
Samples of 5-vinyl-2-norbornene; NMR and GC analysis of the products.

