Table 2.
Effect of concentration of precatalyst 4 on the yield, TON, and TOF of the coupling of 4′-bromoacetophenone (6a) with phenylboronic acid (5) in water.
| Entry | Pd, mol% | Conversion %a,b | TON | TOF (h−1) |
|---|---|---|---|---|
| 1 | 1.00 | 100 | 100 | 33 |
| 2 | 0.75 | 100 (95) | 133 | 44 |
| 3 | 0.50 | 100 | 200 | 66 |
| 4 | 0.25 | 100 | 400 | 133 |
| 5 | 0.125 | 100 | 800 | 266 |
| 6 | 0.05 | 89 | 1780 | 593 |
| 7 | 1.00 (PdCl2/ligand 3)c | 87 | 87 | 26 |
| 8 | 0.00 | 0 | 0 | 0 |
a
Conditions: 4′-bromoacetophenone (6a)/phenylboronic acid (5)/base/TBAB/water: 1/1.2/1/0.6/10 mL, under thermal heating at 100 °C for 3 h.
b
Conversions were based on GC-analysis and the value between parenthesis refer to the highest isolated yield%.
c
Instead of precatalyst 4 1.00 mol% of PdCl2 in the presence of 1.00 mol% of ligand 3 was used.