Immobilized metathesis tungsten oxo alkylidene catalysts and use thereof in olefin metathesis

A method of making an immobilized tungsten catalyst comprising

• (≡SiO)xW(═O)(═(CR1R2)(R3 or R4)2-x(L)z,
• wherein each of R1 and R2 is independently R, —OR, —SR, —N(R)2, —OC(O)R, —SOR, —SO2R, —SO2N(R)2, —C(O)N(R)2, —NRC(O)R, or —NRSO2R;
• each R is independently hydrogen or an optionally substituted group selected from C1-20 aliphatic, C1-20 heteroaliphatic having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, phenyl, ferrocene, a 3-7 membered saturated or partially unsaturated carbocyclic ring, an 8-10 membered bicyclic saturated, partially unsaturated or aryl ring, a 5-6 membered monocyclic heteroaryl ring having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 4-7 membered saturated or partially unsaturated heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, a 7-10 membered bicyclic saturated or partially unsaturated heterocyclic ring having 1-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8-10 membered bicyclic heteroaryl ring having 1-5 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or:
• two R groups on the same nitrogen atom are taken together with the nitrogen to form an optionally substituted 3-12 membered saturated, partially unsaturated, or aryl ring having 0-5 additional heteroatoms not including the same nitrogen atom independently selected from nitrogen, oxygen, or sulfur;
• or:
• two R groups on the same oxygen atom are taken together with the oxygen to form an optionally substituted 3-12 membered saturated, partially unsaturated, or aryl ring having 0-5 additional heteroatoms not including the same oxygen atom independently selected from nitrogen, oxygen, or sulfur;
• R3 and R4 have independently the same meaning as R1 and R2;
• or tris(C1-20 alkyl)silyl, tris(C1-20 alkyl) silyloxy, tris(C1-20 alkoxy)silyl, tris(C1-20 alkoxy)silyloxy, tris (aryl)silyl, tris(aryl)silyloxy, tris(aryloxy)silyl, or tris(aryloxy)silyloxy;
• and
• wherein x=1 or 2;
• z=0, 1 or 2 or a number between 0 and 2;
• and L is a neutral ligand;
• comprising at least the following step (i):
• (i) reacting silica (SiO2) with a tungsten oxo alkylidene complex comprising (R3)(R4)W(═O)(═CR1R2)(L)y, wherein y=0, 1, or 2, wherein L, R1, R2, R3 and R4 have the meaning as defined above, and wherein R3 and R4 additionally may independently have the meaning of halogen, preferably of Cl.