One-pot synthesis of 5-ethylidene-2-norbornene (ENB), which is used as a third component of ethylene-propylene rubbers produced from 1,3-butadiene (BD) and cyclopentadiene (CP) in the presence of Cp2TiCl2-LiAlH4 was investigated. It was found that ENB could be produced in yields up to 35% by one-pot reaction from BD and CP under the influence of Cp2TiCl2 (1/450 mole) and LiAlH4 (4/450 mole) to the starting dienes. Yields of 1:1 adducts other than ENB were almost similar to those of Diels-Alder reaction of BD with CP. 5-Vinyl-2-norbornene (VNB) was isomerized to ENB by Cp2TiCl2-LiAlH4 under similar reaction conditions. The rate of Cope rearrangement from VNB to cis-3a,4,7,7a-tetrahydroindene (THI) was slower than that of isomerization from VNB to ENB. From these results, it was found that VNB formed by the reaction of BD with CP was readily isomerized to ENB without rearranging to THI under the influence of Cp2TiCl2-LiAlH4.