Studies on organolanthanide complexes. XVIII. The reduction and isomerization of olefins with tricyclopentadienyllanthanides/sodium hydride

Article abstract of DOI:10.1016/0022-328X(88)80477-7

Reduction of 1-hexene with Cp3Ln/NaH (Cp=cyclopentadienyl, Ln=rare earth metals) in THF at 45 deg C, after hydrolysis, gives hexane.The reducing activity of Cp3Ln depends strongly upon the ionic radius of the trivalent rare earth ion.The activity and selectivity of early rare earths for 1-hexene reduction are higher than those of heavy rare earths.The Cp3Ln/NaH systems can be used to regioselectively reduce dienes which contain a terminal carbon-carbon double bond as well as an internal one with high yield.Selectivity is 100percent.Moreover, the Cp3Ln/NaH systems are able to catalyze the hydrogenation of olefins.When Cp3Ln/NaH is used as catalyst, 1-hexene was isomerized at 45 deg C to cis-2-hexene and to trans-2-hexene in excellent yields.In contrast to reducing activity, the catalytic activity of heavy rare earths in the isomerization reaction is higher than that of the early earths.Hence, Cp3Sm/NaN and Cp3Y/NaH are new reducing agents and catalysts for 1-hexene reduction and isomerization, respectively.