Ligands for metals and improved metal-catalyzed processes based thereon
One aspect of the present invention relates to ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
1. A ligand represented by structure I:
wherein
R is selected independently for each occurrence from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, aralkyl, heteroaralkyl, and —(CH 2 ) m —R 80 ;
the A and A′ rings of the biphenyl core independently may be unsubstituted or substituted with R 1 and R 2 , respectively, any number of times up to the limitations imposed by stability and the rules of valence;
R 1 and R 2 , when present, are selected independently for each occurrence from the group consisting of ethyl, propyl, butyl, pentyl, hexyl, cycloalkyl, heterocycloalkyl, heteroaryl, aralkyl, heteroaralkyl, —Si(R) 3 , and —(CH 2 ) m —R 80 ;
R 80 represents an unsubstituted or substituted aryl, a cycloalkyl, a cycloalkenyl, a heterocycle, or a polycycle;
m is independently for each occurrence an integer in the range 0 to 8 inclusive; and
the ligand, when chiral, is a mixture of enantiomers or a single enantiomer.
2. The ligand of claim 1 , wherein R represents independently for each occurrence ethyl, propyl, butyl, pentyl, hexyl, cycloalkyl or aryl; at least two instances of R 2 are present; and R 2 is selected independently for each occurrence from the group consisting of ethyl, propyl, butyl, pentyl, hexyl, and cycloalkyl.
3. A ligand represented by structure II:
wherein
R is selected independently for each occurrence from the group consisting of cycloalkyl, and —(CH 2 ) m —R 80 ;
R′ is selected independently for each occurrence from the group consisting of alkyl, cycloalkyl, and —(CH 2 ) m —R 80 ;
the A and A′ rings of the biphenyl core independently may be unsubstituted or substituted with R 1 and R 2 , respectively, any number of times up to the limitations imposed by stability and the rules of valence;
R 1 and R 2 , when present, are selected independently for each occurrence from the group consisting of alkyl, cycloalkyl, halogen, —Si(R) 3 , and —(CH 2 ) m —R 80 ;
R 80 represents independently for each occurrence cycloalkyl or aryl;
m is independently for each occurrence an integer in the range 0 to 8 inclusive; and
the ligand, when chiral, is a mixture of enantiomers or a single enantiomer.
4. The ligand of claim 3 , wherein R 1 is absent; and R 2 is absent.
5. The ligand of claim 3 , wherein R represents independently for each occurrence cycloalkyl.
6. The ligand of claim 3 , wherein R represents independently for each occurrence, cyclohexyl, or cyclopropyl.
7. The ligand of claim 3 , wherein R represents independently for each occurrence cyclohexyl.
8. The ligand of claim 3 , wherein R′ represents independently for each occurrence alkyl.
9. The ligand of claim 3 , wherein R′ represents independently for each occurrence isopropyl.
10. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; and R represents independently for each occurrence cycloalkyl.
11. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; and R represents independently for each occurrence cyclohexyl, or cyclopropyl.
12. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; and R represents independently for each occurrence cyclohexyl.
13. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; R represents independently for each occurrence cycloalkyl; and R′ represents independently for each occurrence alkyl.
14. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; R represents independently for each occurrence cyclohexyl, or cyclopropyl; and R′ represents independently for each occurrence alkyl.
15. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; R represents independently for each occurrence cyclohexyl; and R′ represents independently for each occurrence alkyl.
16. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; R represents independently for each occurrence or cycloalkyl; and R′ represents independently for each occurrence isopropyl.
17. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; R represents independently for each occurrence cyclohexyl, or cyclopropyl; and R′ represents independently for each occurrence isopropyl.
18. The ligand of claim 3 , wherein R 1 is absent; R 2 is absent; R represents independently for each occurrence cyclohexyl; and R′ represents independently for each occurrence isopropyl.
19. A ligand represented by structure III:
wherein
R′ is selected independently for each occurrence from the group consisting of alkyl, cycloalkyl, and —(CH 2 ) m —R 80 ;
the A and A′ rings of the biphenyl core independently may be unsubstituted or substituted with R 1 and R 2 , respectively, any number of times up to the limitations imposed by stability and the rules of valence;
R 1 and R 2 , when present, are selected independently for each occurrence from the group consisting of alkyl, cycloalkyl, halogen, —Si(R) 3 , and —(CH 2 ) m —R 80 ;
R 80 represents independently for each occurrence cycloalkyl or aryl;
m is independently for each occurrence an integer in the range 0 to 8 inclusive; and
the ligand, when chiral, is a mixture of enantiomers or a single enantiomer.
20. The ligand of claim 19 , wherein R 1 is absent; and R 2 is absent.
21. The ligand of claim 19 , wherein R′ represents independently for each occurrence alkyl.
22. The ligand of claim 19 , wherein R′ represents independently for each occurrence isopropyl.
23. The ligand of claim 19 , wherein R 1 is absent; R 2 is absent; and R′ represents independently for each occurrence alkyl.
24. The ligand of claim 19 , wherein R 1 is absent; R 2 is absent; and R′ represents independently for each occurrence isopropyl.