A highly efficient, Z-selective ring-closing metathesis system for the formation of macrocycles using a stereoretentive, ruthenium-based catalyst supported by a dithiolate ligand is reported. This catalyst is demonstrated to be remarkably active as observed in initiation experiments showing complete catalyst initiation at 20 C. within 10 min. Using easily accessible diene starting materials bearing a Z-olefin moiety, macrocyclization reactions generated products with significantly higher Z-selectivity in appreciably shorter reaction times, in higher yield, and with much lower catalyst loadings than in previously reported systems. Macrocyclic lactones ranging in size from twelve-membered to seventeen-membered rings are synthesized in moderate to high yields (68-79% yield) with excellent Z-selectivity (95%-99% Z).

The present invention relates to a catalyst system comprising a transition metal compound on a solid carrier which is a surface-reacted calcium carbonate. The invention further relates to a method for manufacturing said catalyst system and to its use in heterogeneous catalysis.

This invention relates generally to the synthesis of E-macrocycles using stereoretentive ruthenium olefin metathesis catalysts supported by dithioiate ligands. Macrocycles were generated with excellent selectivity (>99% E) and in moderate to high/good yields (47% to 80% yield; 58% to 80% yield) from diene starting materials bearing two E-olefins or bearing one E-olefin and one terminal olefin, A variety of rings were constructed, ranging from 12- to 18-membered macrocycles, including the antibiotic recifeiolide. The invention has utility in the fields of organometallics and organic synthesis.

The present invention discloses a phosphine free cobalt based catalyst of formula (I) and a process for preparation thereof. The present invention further discloses a process for the synthesis of aromatic heterocyclic compounds of formula (II) and pyrazine derivative using the phosphine free cobalt based catalyst of formula (I).

This invention relates generally to metathesis catalysts and the use of such catalysts in the metathesis of olefins and olefin compounds, more particularly, in the use of such catalysts in Z and E selective olefin metathesis reactions. The invention has utility in the fields of organometallics and organic synthesis.

The present invention relates to a process for preparing nitrile rubbers having reduced molecular weight by metathesis of a first nitrile rubber in the presence of specific ruthenium complex catalysts that have particular N-heterocyclic carbene ligands.

The present invention relates to the field of polymerisation catalysts, and systems comprising these catalysts for polymerising carbon dioxide and an epoxide, a lactide and/or lactone, and/or an epoxide and an anhydride. The catalyst is of formula (I): ##STR00001##
wherein at least one of M.sub.1 or M.sub.2 is selected from Ni(II) and Ni(III)-X. A process for the reaction of carbon dioxide with an epoxide; an epoxide and an anhydride; and/or a lactide and/or a lactone in the presence of the catalyst is also described.

Compound of formula 4 or formula 5

##STR00001##

wherein
L is a neutral ligand, preferably a nitrogen-containing heterocyclic carbene (NHC) such as carbene containing at least two nitrogen atoms, a cyclic aminoalkyl carbene (CAAC) or a bicyclic aminoalkyl carbene (BICAAC);
R.sup.1, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are, independently, H, unbranched or branched C.sub.1-20 alkyl, C.sub.5-9 cycloalkyl, unbranched or branched C.sub.1-20 alkoxy, optionally bearing one or more halogen atoms, respectively; or aryl, optionally substituted with one or more of unbranched or branched C.sub.1-20 alkyl, C.sub.5-9 cycloalkyl, unbranched or branched C.sub.1-20 alkoxy, aryl, aryloxy, unbranched or branched C.sub.1-20 alkylcarbonyl, arylcarbonyl, unbranched or branched C.sub.1-20 alkoxycarbonyl, aryloxycarbonyl, heteroaryl, carboxyl, cyano, nitro, amido, aminosulfonyl, N-heteroarylsulfonyl, unbranched or branched C.sub.1-20 alkylsulfonyl, arylsulfonyl, unbranched or branched C.sub.1-20 alkylsulfinyl, arylsulfinyl, unbranched or branched C.sub.1-20 alkylthio, arylthio, sulfonamide, halogen or N(R.sup.y)(R.sup.z), wherein R.sup.y and R.sup.z are independently selected from H and C.sub.1-20 alkyl:
R.sup.2 is H, unbranched or branched C.sub.1-20 alkyl.

Method of forming a trisubstituted ethylene compound, the method comprising: (A) providing a trisubstituted ethylene compound bearing a first, a second and a third substituent, in which the first and the second substituent are bound to the one olefinic carbon atom and are different from one another; (B) providing a monosubstituted ethylene compound or a disubstituted ethylene compound in which the substituents are vicinally bound to the olefinic carbon atoms, bearing at least a fourth substituent, respectively; (C) subjecting the trisubstituted ethylene compound provided in step (A) to a cross-metathesis reaction with olefin provided in step (B) to form said trisubstituted ethylene, wherein the cross-metathesis reaction is catalysed by a transition metal complex bearing ligands from which one ligand is a carbene ligand, wherein the carbene complex is characterized by a MC moiety, wherein M is the transition metal; and wherein the reaction proceeds stereoselectively.

The invention relates to a process for the metathesis of olefins implemented with a catalyst comprising a mesoporous matrix and at least the elements molybdenum and silicon, said elements being incorporated into said matrix by means of at least one precursor comprising molybdenum and silicon and having at least one sequence of SiOMo bonds.