Reactivity of Tungsten-aryloxides with Hydrosilane Cocatalysts in Olefin Metathesis

نویسندگان

  • Ione M. Baibich
  • Carla Kern
چکیده

This reaction allows for new olefins to be synthesized and used as raw materials in polymers, perfumes, drugs and agrochemical industrial products, also serving as the starting point for more complex organic molecules. Catalytic systems are based mainly on the metals W, Mo, Re and Ru. The metal-alkylidenes synthesized by Schrock, [Mo(CHR)(NAr)(OR f ) 2 ], Grubbs, [Ru(CHR)(PCy 3 ) 2 Cl 2 ], Herrmann and Dixneuf are particularly interesting catalysts for olefin metathesis. When a catalyst is not a metal-alkylidene, a cocatalyst is added to generate a metalcarbene, known as the active species for metathesis. The homogeneous system [WCl 6 ]/SnR 4 is extensively studied in the literature and is appropriate for non-functionalized and fuctionalized olefins. Tungsten-aryloxides [WCl 4 (OAr) 2 ] are useful because they can be easily synthesized from [WCl 6 ] and its corresponding phenol and offer good handling stability. Moreover, these compounds are very versatile, because their activity and stereoselectivity can be modified, by changing their ring substituents. Thus, electronegative groups increase the reduction potential of tungsten atoms, enhancing the catalytic activity of these compounds in metathesis. Furthermore, stereoselectivity can be achieved by placing bulky groups in 2,6 positions of the ring. In previous studies we investigated the catalytic activity of a new system based on [WCl 6 ] plus PMHS Reactivity of Tungsten-aryloxides with Hydrosilane Cocatalysts in Olefin Metathesis

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تاریخ انتشار 2002