Highly active multidentate catalysts for efficient alkyne metathesis
AssigneeThe Regents of the University of Colorado, a body corporate
InventorsWei Zhang, Jyothish Kuthanapillil, Qi Wang
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Abstract
The invention relates to highly active and selective catalysts for alkyne metathesis. In one aspect, the invention includes a multidentate organic ligand wherein one substrate-binding site of the metal center is blocked. In another aspect, the invention includes N-quaternized or silane-based multidentate organic ligands, capable of binding to metals. In yet another aspect, the invention includes N-quaternized or silane-based multidentate catalysts. The catalysts of the invention show high robustness, strong resistance to small alkyne polymerization and significantly enhanced catalytic activity compared to their corresponding non-quaternized or non-silane-based multidentate catalyst analogs.
Claims10
A compound of formula (III) or a salt thereof:
- wherein:
- each G is independently alkyl, aryl or heteroaryl, wherein the alkyl, aryl or heteroaryl is optionally and independently substituted with alkyl, halogen or electron-withdrawing substituents;
- R1 is selected from the group consisting of N+R(A−), B, CH, CR, SiR and a 1,3,5-trivalent phenyl moiety, wherein R is optionally substituted alkyl or aryl, and A− is an anion;
- R3 is selected from the group consisting of alkyl, alkyl(aryl) and aryl, all of which are optionally substituted;
- R4 is a single bond, heteroatom, or an optionally substituted C1-C3 alkyl chain;
- and,
- M is a metal.
A method of preparing a compound of formula (IV), comprising reacting a compound of formula (II) with a metal alkylidyne compound with exchangeable ligands:
- wherein:
- R1 is selected from the group consisting of N+R(A−), B, CH, CR, SiR and a 1,3,5-trivalent phenyl moiety, wherein R is optionally substituted alkyl or aryl, and A− is an anion;
- each occurrence of n is independently 0, 1, 2, 3 or 4;
- each occurrence of R2 is independently alkyl, halogen or an electron-withdrawing group;
- R3 is alkyl, alkyl(aryl) or aryl, all of which are optionally substituted;
- M is selected from the group consisting of Mo, W. Re and Ta.
A method of preparing an alkyne-containing metathesis product, comprising contacting a first alkyne-containing substrate with a second alkyne-containing substrate in the presence of a compound of formula (IV) or a salt thereof, whereby the metathesis product of the first and second alkyne-containing substrates is formed:
- wherein:
- each occurrence of n is independently 0, 1, 2, 3, or 4;
- R1 is selected from the group consisting of N+R(A−), B, CH, CR, SiR and a 1,3,5-trivalent phenyl moiety, wherein R is optionally substituted alkyl or aryl, and A− is an anion;
- each occurrence of R2 is independently selected from the group consisting of alkyl, halogen, nitro, cyano, trifluoromethyl, trichloromethyl, carboxy, formyl, lower alkanoyl, carboxyamido and aryl lower alkanoyl;
- R3 is alkyl, alkyl(aryl) or aryl, all of which are optionally substituted;
- and
- M is selected from the group consisting of Mo, W. Re and Ta.
Dependencies are inferred from the claim text.