Lanthanoid complexes alkenes

Actinide and lanthanoid complexes have been employed for hydrogenation reactions, for which they often generate dramatic rate increases and high numbers of turnovers42. Many of these complexes exhibit good selectivity for preferential reduction of the less hindered alkene in situations where more than one is present in a substrate (Scheme l)43. 

In the presence of [Cp2Mo2(CO)4], 3 > [Ni2(COD)2( JL-ri2-RC R)],223 = and [Ni4(RNC)4( X3-V-RC=CR)3], alkynes are converted to ds-alkenes. The alkenes once formed no longer bind to the complex and hydrogenation does not proceed further to give alkanes or even isomerized alkenes. Cocondensation of lanthanoid metal atoms with internal alkynes generates lanthanoid complexes of alkynes, which are potential catalysts for hydrogenation. [ Sm(l-hexyne) n] or [ Er(3-hexyne) n] catalyzes hydrogenation of hex-3-yne to ds-hex-3-ene (97% cis) at room temperature and atmospheric pressure of H2. ... 

Shibasaki has recently described a process for epoxidation of electron-deficient alkenes catalyzed by chiral lanthanoid-BINOL complexes (5-8 mol %) using ferf-butyl hydrogen peroxide [or cumene hydroperoxide (CMHP)] [56]. Epoxides were obtained in excellent yields and enantioselectivities as shown in Scheme 21. 

The allyl and similar 7C-alkenyl complexes of lanthanoids can be prepared in the reactions of cyclopentadieny 1-hydrides with alkenes and dienes [1, 23]. The alkane is evolved in these reactions as a second product... 

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