Functionalization of Octavinylsilsesquioxane by Ruthenium-Catalyzed Silylative Coupling versus Cross-Metathesis

• Published in: Chemistry : a European journal 2004-03, Vol.10 (5), p.1239-1248
• Main Authors: Itami, Y., Marciniec, B., Kubicki, M.
• Format: Article
• Language: English
• Subjects: Catalysis; metathesis; Molecular Structure; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; ruthenium; Ruthenium - chemistry; silsesquioxanes; silylative coupling; Stereoisomerism; Vinyl Compounds - chemical synthesis; Vinyl Compounds - chemistry; vinylsilanes
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200305433

Functionalization of octavinylsilsesquioxane (Vi8T8, 1) by two reactions catalyzed by ruthenium complexes is reported: a silylative coupling reaction catalyzed by [RuHCl(CO)(PCy3)2] (I) and cross‐metathesis catalyzed by first‐ (II) and second‐generation (III) Grubbs’ catalysts. The two reactions of 1 with styrene take place highly regio‐ and stereoselectively (the X‐ray structure of the product 2 has also been obtained); the cross‐metathesis of 1‐hexene and allyltrimethylsilane occurs quite effectively, whereas the silylative coupling with these compounds gives a mixture of isomers. Functionalization of 1 with heteroatom‐substituted vinyl derivatives (Si, O, N) by silylative coupling reaction has been found to be highly efficient, but cross‐metathesis appears to be the more effective method for the synthesis of S‐substituted vinyl‐silsesquioxane. Ruthenium complexes catalyze two types of functionalization reactions of octavinylsilsesquioxane (Vi8T8), a silylative coupling reaction (catalyzed by [RuHCl(CO)(PCy3)2]) and cross‐metathesis (catalyzed by first‐ and second‐generation Grubbs' catalysts) with styrene, α‐olefins, and vinyl‐heteroatom substituted compounds (see scheme).