Ethyl oleate tungsten catalysts

ABSTRACT. Cyclometalated aryloxy(chloro)neopentylidene-tungsten complexes can be synthesized starting from WCl4(OAr)2 (OAr = 2,6-disubstituted phenoxide), but also starting from the neopentylidyne complex W(CCMe3)Cl3(dme) (by reaction with LiOAr). Some of these cyclometalated neopentylidenes are probably among the most active and stereoselective one-component metathesis catalysts. In particular, they are fairly active in the metathesis of an olefinic ester such as ethyl oleate and they have been successfully used in the metathesis of olefinic sulfides. 

Initial reports of cross-metathesis reactions using well-defined catalysts were limited to simple isolated examples the metathesis of ethyl or methyl oleate with dec-5-ene catalysed by tungsten alkylidenes [13,14] and the cross-metathesis of unsaturated ethers catalysed by a chromium carbene complex [15]. With the discovery of the well-defined molybdenum and ruthenium alkylidene catalysts 3 and 4,by Schrock [16] and Grubbs [17],respectively, the development of alkene metathesis as a tool for organic synthesis began in earnest. 

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