TABLE 5.
Homocoupling of Arylboronic Acidsa
| ||||
|---|---|---|---|---|
| entry | Pd(OAc)2 | Cu(OAc)2 | CuCl2 | 6 (%) |
| 1 | 10 mol% | 2 equiv | 2 equiv | 70 |
| 2 | 10 mol% | 2 equiv | none | 82 |
| 3 | 10 mol% | none | 2 equiv | 9 |
| 4 | none | 2 equiv | 2 equiv | 14 |
| 5 | none | 2 equiv | none | 25 |
| 6 | none | none | 2 equiv | 6 |
Reaction conditions: 2a (0.4 M) in DMF under N2 at 60 °C for 1 h.