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A general method for the functionalization of Si−Cl terminated carbosilane dendritic molecules via organolithium or organomagnesium reagents is described. Quantitative exchange of the bromine atoms of 4-bromophenyl-functionalized dendrimers affords polylithiated species that are valuable starting materials for further functionalization, e.g., into pyridyl alcohols. The latter were successfully applied as catalyst precursors in a ruthenium-mediated ring-closure metathesis reaction.Among the many potential applications 1 of dendrimers, the immobilization of catalytically active sites at the periphery of these molecules is of current interest. The first example was the successful use of an arylnickel-functionalized carbosilane as a homogeneous catalyst in the Kharasch addition of polyhalogenoalkanes to CdC double bonds. 2 Today, a number of dendritic molecules are known that contain ligand systems at their periphery to which metal atoms may be bound covalently or via heteroatom donor bonds. This topic has been reviewed recently. 3,4 So far, only a few examples of such metallo-dendrimers have been applied as immobilized catalysts. A recent development is the use of metallo-dendrimers as low-conversion catalysts in continuous membrane-reactor processes. An example is the selective hydrovinylation of styrene with an in situ prepared palladium catalyst immobilized on a carbosilane (CS) dendrimer. 5 Similar examples are palladium-catalyzed C-C bond formation reactions using bisphosphine-containing CS-dendrimers 6 or diaminopropyl-type dendrimers. 7 Peripheral functional groups are often connected to the dendrimer core via heteroatom-containing linkers such as † Utrecht University. ‡ Ciba Specialty Chemicals. (1)

A simple one-pot procedure for the synthesis of ruthenium benzylidenes (Grubbs' catalyst) has been developed in which a novel, highly reactive 14-electron ruthenium monohydride, prepared from [RuCl 2 (cod)] and two bulky phosphines in boiling propan-2-ol without the use of hydrogen gas, is reacted with hydrogen chloride, an alkyne and styrene.

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