Olefin Disproportionation Exchange of Alkylidene Groups

Transition metal-catalyzed olefin disproportionation [Eq. (149) (R = alkyl, aryl R = heteroatom such as Cl deactivates the double bond toward the metathesis reaction)] has been used very little in organic synthesis, but the reaction has considerable potential and has been the subject of several reviews (Banks, 1972 Calderon, 1972 Hughes, 1972 Cardin et al., 1973 Haines and Leigh, 1975). 

Cyclic olefins readily undergo transalkylidenation with other cyclic olefins to give large ring dienes, but, of course, the product reacts further with other cyclic olefin molecules, leading to a polymeric mixture of macrocyclic rings. 

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