Other Organolanthanide-catalyzed Reactions

The monomeric lanthanocene Schiff base complexes Cp2Ln(OC14H13NO) (Ln = Sm, Er, Dy, Y) in the presence of NaH have been found to catalyze the isomerization of 1,5-hexadiene. The isomerization results in a mixture of 1,4-hexadiene, 2,4-hexadiene, 1,3-hexadiene, methylenecyclopentane, and methylcyclopentane. The ratio of linear to 

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This organolanthanide-catalyzed reaction provides the first example of efficient preparation of well-defined propiolamidines, a new family of amidines which are difficult to access by other means and may show unique reactivity. A wide range of terminal alkynes could be used for this catalytic cross-coupling reaction which was not affected by either electron-withdrawing or -donating substituents or their positions at the phenyl ring of the aromatic alkyne [68]. 

Complexes of the 4 type catalyze the hydroboration of various olefins with catecholborane at ambient temperature [173], The proposed mechanism of the hydroboration reaction - although not within the scope of this book - parallels that of the hydrogenation and hydrosilylation reactions. The architecture of both olefins (terminal > terminal disubstituted > internal disubstituted > trisubstituted) and organolanthanides (TOF(La) 10 TOF(Sm) TOF(5) = 4 TOF(4) affects the rate of hydroboration, which for 4(La CH(SiMc3)2) and 1-hexene is TOF = 200 h , for example. The observed high regioselectivities are exclusively anti-Markovnikov. For smaller metal centers (Y, Zr, Ti) and other ligand systems (bis(cyclopentadienyl), bis(benzamidinato)) inactivation of the catalyst by catecholborane or Lewis base-metal complex induced disproportionation of catecholborane appeared to compete effectively with the catalytic conversion [174]. 

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