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"A Posteriori" Modification of Carbosilane Dendrimers and Dendrons: Their Activation in Core and Branch Positions

"A Posteriori" Modification of Carbosilane Dendrimers and Dendrons: Their Activation in Core and Branch Positions

Arno Tuchbreiter, Helmut Werner, Lutz H Gade

Dalton Trans. 2005 Apr 21;(8):1394-402.

PMID: 15824777

Abstract:

The introduction of phenyl groups at different points on carbosilane dendrimers allows their acidolytic conversion to highly reactive triflato groups which in turn are readily substituted by anionic nucleophiles. Core phenylated first-fourth generation dendrimers were synthesized from tri(allyl)phenylsilane by an alternating sequence of hydrosilylation and allylation steps. Similarly, carbosilane dendrimers containing phenyl-Si groups at the branching points and in the periphery were prepared from tetraallylsilane which was hydrosilylated with PhHSiCl2. Reaction of the phenylated dendrimers with triflic acid in toluene cleanly gave the silyl triflate derivatives, provided that the correct stoichiometry of the reagents was used. In the presence of a large excess of triflic acid the SiMe3-end groups are slowly converted to SiMe2(OTf)-units. The proof of concept was provided by the fixation of a {Ph2PCH2} group using the lithiated diphenylphosphinomethanide Ph2PCH2Li, obtained by cleavage of Ph3SnCH2PPh2 with PhLi, as well as a lithiated ether-alcohol functionalized triphos derivative to the core of a third generation carbosilane dendrimer.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP1112669	Tetraallylsilane		1112-66-9	Price

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