ARYLOXIDE LIGANDS IN METATHESIS OF OLEFINS AND OLEFINIC ESTERS - CATALYTIC BEHAVIOR OF W(OAR)2CL4 COMPLEXES ASSOCIATED WITH ALKYL-TIN OR ALKYL-LEAD COCATALYSTS - ALKYLATION OF W(OAR)2CL4 BY SNME4, SN(N-BU)4, PB(N-BU)4, MGNP2 - SYNTHESIS OF W(OAR)2CL2(CHCME3)(OR2) AND W(OAR)2CL(CHCME3)(CH2CME3)(OR2)

The authors report on the 'metathetic' properties (activity, stereoselectivity) of the precursor complexes W(OAr)//2Cl//4 (OAr equals O-2,6-C//6H//3Me//2 (1), O-2,6-C//6H//3(C//6H//5)//2 (2), O-2,6-C//6H//3Br//2 (3), O-2,6-C//6H//3Cl//2 (4) and O-2,6-C//6H//3F//2 (5) when they are associated with SnMe//4, Sn(n-Bu)//4 or Pb(n-Bu)//4. The reactions which have been studied are metathesis of internal or terminal olefins, metathesis of olefinic esters or cross-metathesis between olefinic esters and olefins. In order to determine the coordination sphere of the real catalyst, the alkylation of the precursors W(OAr)//2Cl//4 by SnMe//4 Sn(n-Bu)//4, Pb(n-Bu)//4 and MgNp//2 has been studied in detail.