Cyclic alkyl amino carbene (CAAC) ruthenium complexes as improved catalysts for ethenolysis reactions
Described herein are compounds and methods of catalyzing ethenolysis reactions, optionally on an industrial scale. In certain embodiments, the catalysts bear cyclic alkyl amino carbene (CAAC) ligands with an ortho substituent, such as a methyl substituent, on an N-aryl ring. When used to catalyze ethenolysis reactions, certain such compounds produce a turnover number greater than 50,000.
1. A compound, wherein the compound is
(A) a compound of Formula I:
wherein, independently for each occurrence,
X is, independently for each occurrence, alkoxy or halo;
R 2 is, independently for each occurrence, alkyl;
R 3 is alkyl;
R 4 is alkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl;
or R 3 and R 4 , taken together with the carbon atom to which they are attached, form a five-, six-, or ten-membered cycloalkyl or heterocyclyl ring;
R 5 is alkyl;
R 6 is H or alkyl, provided that (i) R 5 and R 6 are not the same, and (ii) R 6 has fewer atoms than R 5 ; and
R 7 is alkyl;
(B) a compound of Formula II:
wherein, independently for each occurrence,
X is, independently for each occurrence, alkoxy or halo;
R 2 is, independently for each occurrence, alkyl;
R 3 is alkyl;
R 4 is alkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl;
or R 3 and R 4 , taken together with the carbon atom to which they are attached, form a five-, six-, or ten-membered cycloalkyl or heterocyclyl ring;
R 5 is, independently for each occurrence, alkyl; and
R 7 is alkyl;
(C) a compound of Formula III:
wherein, independently for each occurrence,
X is, independently for each occurrence, alkoxy or halo;
R 2 is alkyl;
R 3 is alkyl;
R 5 is, independently for each occurrence, methyl or ethyl;
R 7 is alkyl; and
R 8 is aryl or heteroaryl; or
(D) a compound of Formula IV:
wherein, independently for each occurrence,
X is, independently for each occurrence, alkoxy or halo;
R 2 is alkyl;
R 3 is alkyl;
R 5 is, independently for each occurrence, alkyl;
R 7 is alkyl; and
R 9 is C 2 -C 6 alkyl;
or R 3 and R 9 , taken together with the carbon atom to which they are attached, form a five-, or ten-membered cycloalkyl or heterocyclyl ring.
2. The compound of claim 1 , wherein X is chloro.
3. The compound of claim 1 , wherein R 2 is methyl.
4. The compound of claim 1 , wherein R 3 is ethyl or methyl.
5. The compound of claim 1 , wherein the compound is a compound of Formula I or a compound of Formula II; and R 4 is ethyl or methyl.
6. The compound of claim 1 , wherein the compound is a compound of Formula I or a compound of Formula II; and R 4 is phenyl.
7. The compound of claim 1 , wherein the compound is a compound of Formula I or a compound of Formula II; and R 3 and R 4 , taken together with the carbon atom to which they are attached, form a cyclohexyl ring.
8. The compound of claim 1 , wherein the compound is a compound of Formula I, Formula II, or Formula IV, and R 5 is methyl, ethyl, iso-propyl, or tert-butyl.
9. The compound of claim 1 , wherein the compound is a compound of Formula I; and R 6 is H or methyl.
10. The compound of claim 1 , wherein R 7 is iso-propyl.
11. The compound of claim 1 , wherein the compound is a compound of Formula III; and R 8 is phenyl.
12. The compound of claim 1 , wherein the compound is a compound of Formula IV; and R 9 is n-propyl.
13. A compound selected from:
14. A method of producing an olefin product comprising:
providing an olefinic substrate;
providing an alpha olefin;
contacting the olefinic substrate with the alpha olefin in the presence of a compound of claim 1 under reaction conditions effective to allow a metathesis reaction to occur, thereby producing the olefin product.
15. The method of claim 14 , wherein the olefin product is a terminal olefin product.
16. The method of claim 14 , wherein the olefinic substrate comprises at least one internal olefin.
17. The method of claim 14 , wherein the olefinic substrate is a cyclic olefin.
18. The method of claim 14 , wherein the olefinic substrate is an ester of glycerol.
19. The method of claim 14 , wherein the olefinic substrate is a seed oil.
20. The method of claim 19 , wherein the seed oil is selected from: soybean oil, sunflower oil, canola oil, safflower oil, cottonseed oil, castor oil, rape seed oil, peanut oil, corn oil, olive oil, palm oil, sesame oil, grape seed oil, algae oil, mustard oil, tung oil, perilla oil, linseed oil, pumpkin oil, cucumber oil, poppyseed oil, flax seed oil, walnut oil, and sesame oil.
21. The method of claim 14 , wherein the turnover number is at least 50,000.