Abstract: The invention relates to a method of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising step (i): (i) reacting the first olefin with the second olefin in the presence of a compound that catalyzes said metathesis reaction such that the molar ratio of said compound to the first or the second olefin is from 1:500 or less, and the conversion of the first or the second olefin to said olefin is at least 50%, characterized in that as compound that catalyzes said metathesis reaction a compound of the following formula is used: wherein M is Mo or W; R1 is aryl, heteroaryl, alkyl, or heteroalkyl; optionally substituted; R2 and R3 can be the same or different and are hydrogen, alkyl, alkenyl, heteroalkyl, heteroalkenyl, aryl, or heteroaryl; optionally substituted; R5 is alkyl, alkoxy, heteroalkyl, aryl, heteroaryl, silylalkyl, silyloxy, optionally substituted; and R4 is a residue R6—X—, wherein X?O and R6 is aryl, optionally substituted; or X?S and R6 is aryl, opt

Abstract: A compound of formula (I) wherein: M is selected from Mo or W; X is selected from O or NR5; R1 and R2 are independently selected from H, C1-6 alkyl, and aryl; C1-6 alkyl and aryl optionally being substituted with one or more of C1-6 alkyl, C1-6 alkoxy, and O—C6H5; R3 is selected from a nitrogen-containing aromatic heterocycle being bound to M via said nitrogen; and from halogen; R4 is an aryl oxy group being bound to M via said oxygen of said aryl oxy group; wherein said aryl group Ar of said aryl oxy group is bound to a group Cat such to form a cationic ligand Cat+-Z—ArO—, wherein Z is either a covalent bond or a linker; R5 is alkyl or aryl, optionally substituted.

Abstract: The invention relates to a method of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising step (i): (i) reacting the first olefin with the second olefin in the presence of a compound that catalyzes said metathesis reaction such that the molar ratio of said compound to the first or the second olefin is from 1:500 or less, and the conversion of the first or the second olefin to said olefin is at least 50%, characterized in that as compound that catalyzes said metathesis reaction a compound of the following formula is used: wherein M is Mo or W; R1 is aryl, heteroaryl, alkyl, or heteroalkyl; optionally substituted; R2 and R3 can be the same or different and are hydrogen, alkyl, alkenyl, heteroalkyl, heteroalkenyl, aryl, or heteroaryl; optionally substituted; R5 is alkyl, alkoxy, heteroalkyl, aryl, heteroaryl, silylalkyl, silyloxy, optionally substituted; and R4 is a residue R6—X—, wherein X=O and R6 is aryl, optionally substituted; or X=S and R6 is aryl, opt

Abstract: A method is provided of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising reacting the first olefin with the second olefin in the presence of a compound that catalyzes the metathesis reaction such that the molar ratio of the compound to the first or the second olefin is from 1:500 or less, and the conversion of the first or the second olefin to the olefin is at least 30%.

Abstract: Method of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising step (i): (i) reacting the first olefin with the second olefin in the presence of a silica supported Mo- or W-alkylidene catalyst, wherein the first olefin and the second olefin are different from one another.

Abstract: The invention relates to a method of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising step (i): (i) reacting the first olefin with the second olefin in the presence of a compound that catalyzes said metathesis reaction such that the molar ratio of said compound to the first or the second olefin is from 1:500 or less, and the conversion of the first or the second olefin to said olefin is at least 50%, characterized in that as compound that catalyzes said metathesis reaction a compound of formula (A) is used: wherein M is Mo or W; R1 is aryl, heteroaryl, alkyl, or heteroalkyl; optionally substituted; R2 and R3 can be the same or different and are hydrogen, alkyl, alkenyl, heteroalkyl, heteroalkenyl, aryl, or heteroaryl; optionally substituted; R5 is alkyl, alkoxy, heteroalkyl, aryl, heteroaryl, silylalkyl, silyloxy, optionally substituted; and R4 is a residue R6—X—, wherein X?O and R6 is aryl, optionally substituted; or X?S and R6 is aryl, optionally substituted; or

Abstract: Method of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising step (i): (i) reacting the first olefin with the second olefin in the presence of a silica supported Mo- or W-alkylidene catalyst, wherein the first olefin and the second olefin are different from one another.

Abstract: The invention relates to a method of forming an olefin from a first olefin and a second olefin in a metathesis reaction, comprising step (i): (i) reacting the first olefin with the second olefin in the presence of a compound that catalyzes said metathesis reaction such that the molar ratio of said compound to the first or the second olefin is from 1:500 or less, and the conversion of the first or the second olefin to said olefin is at least 50%, characterized in that as compound that catalyzes said metathesis reaction a compound of formula (A) is used: wherein M is Mo or W; R1 is aryl, heteroaryl, alkyl, or heteroalkyl; optionally substituted; R2 and R3 can be the same or different and are hydrogen, alkyl, alkenyl, heteroalkyl, heteroalkenyl, aryl, or heteroaryl; optionally substituted; R5 is alkyl, alkoxy, heteroalkyl, aryl, heteroaryl, silylalkyl, silyloxy, optionally substituted; and R4 is a residue R6—X—, wherein X?O and R6 is aryl, optionally substituted; or X?S and R6 is aryl, optionally substituted; or