Table 2.
Optimization of t-Butylketone-Substituted Electrophile: Effect of Ligand
 | |||||
|---|---|---|---|---|---|
| Entrya | Pd (mol%) | PR3 (mol%) | Yield [%]b | E:Zc | erd |
| 1 | PdXantphos G3 | -- | 45 | E only | 85:15 |
| 2 | Pd2dba3(5) | Xantphos (10) | 41 | E only | -- |
| 3 | Pd2dba3(5) | DPEphos (10) | 0 | -- | -- |
| 4 | Pd2dba3(5) | dppf (10) | 36 | E only | - |
| 5 | Pd2dba3(5) | dppe (10) | 0 | -- | - |
| 6 | Pd2dba3(5) | PCy3 (20) | NA | NA | NA |
| 7 | Pd2dba3(5) | P(o-tolyl)3 (20) | NA | NA | NA |
| 8 | Pd2dba3(5) | P(4-OMePh)3 (20) | 0 | -- | - |
| 9 | Pd2dba3(5) | P(2-furyl)3 (20) | 50 | E only | - |
| 10 | Pd2dba3(5) | P(2-thienyl)3 (20) | 70 | E only | 86:14 |
| 11 | Pd2dba3(5) | P(2-thienyl)3(10) | 70 | E only | 93:7 |
| 12 | Pd2dba3 (10) | P(2-thienyl)3 (25) | 70 | E only | 93:7 |
| 13 | Pd[P(2-thienyl)3]3 (5) | -- | 87 | E only | 96:4 |
a
Reactions performed on a 0.1 mmol scale.
b
Yields determined by 1H NMR by comparison with an internal standard (1,2,4,5-tetramethylbenzene).
c
E/Z ratio calculated from crude 1H NMR.
d
Determined by chiral HPLC analysis