Nickel pre-catalysts and related compositions and methods
Described herein are nickel pre-catalysts and related compositions and methods. The nickel pre-catalysts may be activated to form catalysts which may be utilized in organic reactions.
1. A pre-catalyst, comprising:
a nickel (II) atom, wherein the nickel (II) atom is associated with at least one phosphine ligand; at least one aryl ligand; and at least one leaving group, wherein one or more of the ligands is chiral.
2. The pre-catalyst of claim 1 , wherein the pre-catalyst comprises two phosphine ligands.
3. The pre-catalyst of claim 1 , wherein the pre-catalyst comprises two phosphine ligands, one aryl ligand, and one leaving group.
4. The pre-catalyst of claim 2 , wherein the two phosphine ligands are trans.
5. The pre-catalyst of claim 2 , wherein the two phosphine ligands are cis.
6. The pre-catalyst of claim 2 , the two phosphine ligands are monodentate.
7. The pre-catalyst of claim 1 , wherein the pre-catalyst has the structure:
wherein each R 1 is independently optionally substituted alkyl, optionally substituted cycloalkyl, or optionally substituted aryl, or any two R 1 may be joined together to form a ring;
Ar is the at least one aryl ligand, and LG is the at least one leaving group.
8. The pre-catalyst of claim 1 , wherein the pre-catalyst has the structure:
wherein each R 2 is independently optionally substituted alkyl, optionally substituted cycloalkyl, or optionally substituted aryl, or any two R 2 are joined together to form a ring;
each R 3 is —O—, optionally substituted alkylene, optionally substituted heteroalkylene, optionally substituted arylene, optionally substituted heteroarylene, or optionally substituted ferrocenylene;
n is 1, 2, 3, 4, 5, or 6; Ar is the at least one aryl ligand; and
LG is the at least one leaving group.
9. The pre-catalyst of claim 1 , wherein the pre-catalyst is not:
10. A pre-catalyst, comprising:
a nickel (II) atom, wherein the nickel (II) atom is associated with at least one N-heterocyclic carbene ligand; at least one aryl ligand; and at least one leaving group.
11. The pre-catalyst of claim 10 , wherein the pre-catalyst further comprises at least one phosphine ligand.
12. The pre-catalyst of claim 10 , wherein the pre-catalyst comprises one heterocyclic carbene ligand, one phosphine ligand, one aryl ligand, and one leaving group.
13. The pre-catalyst of claim 11 , wherein the phosphine ligand is monodentate.
14. The pre-catalyst of claim 1 , wherein each monodentate phosphine ligand is the same or different and has the structure P(R 1 ) 3 , wherein each R 1 is independently optionally substituted alkyl, optionally substituted cycloalkyl, or optionally substituted aryl.
15. The pre-catalyst of claim 1 , wherein the pre-catalyst comprises a bidentate phosphine ligand.
16. The pre-catalyst of claim 15 , wherein the bidentate phosphine ligand has the structure (R 2 ) 2 P—(R 3 ) n —P(R 2 ) 2 , wherein each R 2 is independently optionally substituted alkyl, optionally substituted cycloalkyl, or optionally substituted aryl, or any two R 2 can be joined together to form a ring; each R 3 is —O—, optionally substituted alkylene, optionally substituted heteroalkylene, optionally substituted arylene, optionally substituted heteroarylene, or optionally substituted ferrocenylene; and n is 1, 2, 3, 4, 5, or 6.
17. The pre-catalyst of claim 1 , wherein the aryl ligand is substituted at one or both ortho positions.
18. The pre-catalyst of claim 1 , wherein the leaving group is selected from the group consisting of halo, OTs, and OMs.
19. A method, comprising:
activating a pre-catalyst as in claim 1 to form a catalyst.
20. A compound selected from the group consisting of trans-(PPh 3 ) 2 Ni(o-tolyl)Cl, trans-(PCyPh 2 ) 2 Ni(o-tolyl)Cl, trans-(PCy 2 Ph) 2 Ni(o-tolyl)Cl, trans-(PCy 3 ) 2 Ni(o-tolyl)Cl, trans-(PCy 3 ) 2 Ni(o-tolyl)Cl, trans-(PCy 3 ) 2 Ni(o-tolyl)Cl, trans-(PCyp 3 ) 2 Ni(o-tolyl)Cl, trans-(PCyp 3 ) 2 Ni(o-tolyl)Cl, trans-(PBn 3 ) 2 Ni(o-tolyl)Cl, trans-(PBn 3 ) 2 Ni(o-tolyl)Cl, trans-(PMe 2 Ph) 2 Ni(o-tolyl)Cl, trans-(PMe 2 Ph) 2 Ni(2,4,6-triisopropylphenyl)Br, trans-(PMe 2 Ph) 2 Ni(2,6-dimethoxyphenyl)Br, trans-(PEt 3 ) 2 Ni(2-mesityl)Br, trans-(PnBu 3 ) 2 Ni(2-mesityl)Br, cis-[dppe]Ni(o-tolyl)Cl, cis-[dppp]Ni(2-mesityl)Br, trans-[dppb]Ni(2-mesityl)Br, cis-[(S)-BINAP]Ni(o-tolyl)Cl, cis-[dppf]Ni(o-tolyl)Cl, trans-[dcpf]Ni(o-tolyl)Cl, trans-[xantphos]Ni(o-tolyl)Cl, and cis-[pyphos]Ni(o-tolyl)Cl, wherein:
Cy is cyclohexyl,
Cyp is cyclopentyl,
Bn is benzyl,
dppe is 1,2-bis(diphenylphosphino)ethane,
dppp is 1,3-bis(diphenylphosphino)propane,
dppb is 1,4-bis(diphenylphosphino)butane,
BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl,
dppf is 1,1′-bis(diphenylphosphino)ferrocene,
dcpf is 1,1′-bis(dicyclohexylphosphino)ferrocene,
xantphos is 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene, and
pyphos is 2-[2-(diphenylphosphino)ethyl]pyridine.
21. The compound of claim 20 , wherein the compound is trans-(PCy 3 ) 2 Ni(o-tolyl)Cl, wherein Cy is cyclohexyl.
22. The compound of claim 20 , wherein the compound is trans-(PCy 2 Ph) 2 Ni(o-tolyl)Cl, wherein Cy is cyclohexyl.
23. The compound of claim 20 , wherein the compound is trans-(PCyp 3 ) 2 Ni(o-tolyl)Cl, wherein Cyp is cyclopentyl.
24. The compound of claim 20 , wherein the compound is trans-(PEt 3 ) 2 Ni(2-mesityl)Br.
25. The compound of claim 20 , wherein the compound is trans-(PBn 3 ) 2 Ni(o-tolyl)Cl, wherein Bn is benzyl.
26. The compound of claim 20 , wherein the compound is trans-(PPh 2 Me) 2 Ni(o-tolyl)Cl.
27. The compound of claim 20 , wherein the compound is cis-(dppe)Ni(o-tolyl)Cl, wherein dppe is 1,2-bis(diphenylphosphino)ethane.
28. The compound of claim 20 , wherein the compound is cis-[(S)-BINAP)]Ni(o-tolyl)Cl, wherein BINAP is 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl.
29. A method, comprising:
activating a pre-catalyst as in claim 20 to form a catalyst.