Vinylnorbornene: Preparation, chemical transformations, and use in organic synthesis and polymer chemistry. Vinylnorbornene synthesis and isomerization to ethylidenenorbornene (Review)

The last reviews devoted to the synthesis of 5-vinyl-2-norbornene and its isomerization to 5-ethylidene-2-norbornene were published in 1976-1977. The interest in the practical and theoretical aspects of this problem still does not wane, thus stimulating further investigations. A large number of patents and scientific articles have been published in the last 30 years and need to be summarized. This review elucidates the state of art of manufacture of 5-ethylidene-2-norbornene, the best third monomer for ethylene-propylene rubber. The results of new investigations concerning the manufacture of 5-vinyl-2-norbornene and its isomerization to 5-ethylidene-2-norbornene and vinylnortricyclene are considered. The most active base and coordination catalysts that have found application in industry are characterized. The mechanisms and stereochemistry of 5-vinyl2-norbornene isomerization are discussed.