Terminal alkene monoisomerization catalysts and methods
The invention provides novel catalysts and methods of using catalysts for controlling the position of a double bond and cis/trans-selectivity in isomerization of terminal alkenes to their 2-isomers. Catalysts such as (pentamethylcyclopentadienyl)Ru formulas 1 and 3 having a bifunctional phosphine can be used in the methods. A catalyst loading of 1 mol % of formulas 1+3 can be employed for the production of (E)-2-alkenes at 40-70° C.; lower temperatures can be used with higher catalyst loading. Acetonitrile-free catalysts can be used at lower loadings, room temperature, and in less than a day to accomplish the same results as catalysts 1+3. The novel catalyst systems minimize thermodynamic equilibration of alkene isomers, so that the trans-2-alkenes of both non-functionalized and functionalized alkenes can be generated.
1. An alkene isomerization catalyst of Formula I, Formula II, Formula III, Formula IV, or a combination thereof:
wherein
each R P is independently a branched (C 3 -C 10 )-alkyl, (C 3 -C 10 )-cycloalkyl, (C 3 -C 15 )-alkenyl, (C 2 -C 12 )-alkynyl, heterocyclyl, or an optionally substituted aryl or heteroaryl;
each R L is independently a neutral or anionic ligand, or is absent, provided that at least one R L is not absent when the catalyst is a catalyst of Formula II or Formula IV;
each R A , R B and R C is independently hydrogen, a branched or linear (C 1 -C 20 )-alkyl, (C 3 -C 10 )-cycloalkyl, (C 3 -C 15 )-alkenyl, (C 2 -C 12 )-alkynyl, heterocyclyl, or an optionally substituted aryl or heteroaryl; and
X − is a counterion.
2. The catalyst of claim 1 wherein R P is iso-propyl, iso-butyl, tent-butyl or 1-adamantyl.
3. The catalyst of claim 1 wherein R L is alkyl nitrile, cycloalkyl nitrile, aryl nitrile, heteroaryl nitrile, heterocycloalkyl nitrile, alkylcarbonyl, CO, alkylamine, alkenylamine, arylamine, amide, alkanol, water, (C 3 -C 15 )-alkenol, cycloalkanol, aryl alcohol, ketone, ether, aldehyde, alkene, halo, carboxylate, sulfonyl, sulfonate, phosphonyl, phosphinyl, or N 2 .
4. The catalyst of claim 3 wherein R L is carbonyl, CO, alkylamine, alkenylamine, arylamine, amide, alkanol, water, (C 3 -C 15 )-alkenol, cycloalkanol, aryl alcohol, ketone, ether, aldehyde, alkene, halo, carboxylate, sulfonyl, sulfonate, phosphonyl, phosphinyl, or N 2 .
5. The catalyst of claim 3 wherein R L is acetonitrile, acetone or THF.
6. The catalyst of claim 1 wherein X − is an inorganic halide, CF 3 SO 3 − , BF 4 − , BPh 4 − , B(C 6 F 5 ) 4 − , or B[C 6 H 3 -3,5-(CF 3 ) 2 ] 4 − .
7. The catalyst of claim 6 wherein X − is PF 6 − .
8. The catalyst of claim 1 wherein the catalyst is a mixture of Formula I and Formula II or a mixture of Formula III and Formula IV.
9. The catalyst of claim 1 wherein the catalyst is formula 1:
10. The catalyst of claim 1 wherein the catalyst is formula 3:
11. A catalyst comprising a mixture of formula 1 and formula 3:
12. The catalyst of claim 11 wherein the ratio of formula 1 to formula 3 is from about 1:2 to about 1:5.
13. The catalyst of claim 1 wherein the catalyst is formula 8:
wherein each S is independently solvent, N 2 , or absent, provided that at least one S is not absent.
14. The catalyst of claim 1 wherein the catalyst is formula 9:
wherein S is solvent, N 2 , or absent.
15. The catalyst of claim 1 wherein the catalyst is a mixture of formula 8 and formula 9:
wherein each S is independently solvent, N 2 , or absent, provided that at least one S of formula 8 is not absent.
16. A method of isomerizing a 1-alkene to an E-2-alkene comprising contacting a 1-alkene in a reaction mixture with an effective amount of a catalyst of Formula I, Formula II, Formula III, Formula IV, or a combination thereof:
wherein
each R P is independently a branched (C 3 -C 10 )-alkyl, (C 3 -C 10 )-cycloalkyl,(C 3 -C 15 )-alkenyl, (C 2 -C 12 )-alkynyl, heterocyclyl, or an optionally substituted aryl or heteroaryl;
each R L is independently a neutral or anionic ligand, or is absent, provided that at least one R L is not absent when the catalyst is a catalyst of Formula II or Formula IV;
each R A , R B and R C is independently hydrogen, a branched or linear (C 1 -C 20 )-alkyl, (C 3 -C 10 )-cycloalkyl, (C 3 -C 15 )-alkenyl, (C 2 -C 12 )-alkynyl, heterocyclyl, or an optionally substituted aryl or heteroaryl; and
X − is a counterion;
wherein the reaction mixture optionally includes a suitable solvent, and the method is carried out for a period of time sufficient to convert at least about 70% of the 1-alkene to an E-2-alkene.
17. The method of claim 16 wherein the reaction mixture comprises about 0.01 mol % to about 20 mol % of the catalyst.
18. The method of claim 16 wherein the temperature of the reaction mixture is about 20° C. to about 100° C.
19. The method of claim 18 wherein the catalyst is a mixture of Formula I and Formula II or a mixture of Formula III and Formula IV.
20. The method of claim 16 wherein R L is alkylcarbonyl, CO, alkylamine, alkenylamine, arylamine, amide, alkanol, water, (C 3 -C 15 )-alkenol, cycloalkanol, aryl alcohol, ketone, ether, aldehyde, alkene, halo, carboxylate, sulfonyl, sulfonate, phosphonyl, phosphinyl, or N 2 .
21. The catalyst of claim 1 wherein X − an alkoxide, a carboxylate, a sulfonate, a borate, a phosphate, or an inorganic halide.
22. The method of claim 16 wherein X − an alkoxide, a carboxylate, a sulfonate, a borate, a phosphate, or an inorganic halide.