Table 4.
Hindered Phenolsa
| |||||
|---|---|---|---|---|---|
| Entry | Phenol | 3% Remainingb | 4% Yieldb,c | 6% Yieldb,c | erd |
| 1 |
|
5 | 4k, 67 (50) | 6k, 14 (9) | 97:3 |
| 2 |
|
7 | 4l, 60 (43) | 6l, 15 (14) | 97:3 |
| 3 |
|
7 | 4m, 53 (43) | 6m, 13 (8) | 99:1 |
| 4 |
|
3 | 4n, 33 (33) | 6n, 14 (6) | 97:3 |
| 5 |
|
4 | 4o, 18 (10) | 6o, 0 | 96:4 |
Reported results are the average of two trials. Reaction conditions: 3 (0.2 mmol), phenol (1.3 equiv), Cu(MeCN)4BF4 (10 mol %), peptide (20 mol %), K3PO4 (4.0 equiv.) and MeCN (0.8 mL), 60 °C.
Yield was determined using 1H NMR by comparing to an internal NMR standard (1,4-bis(trimethylsilyl)benzene).
The numbers in parentheses are isolated yields.
Enantiomeric ratios were determined using chiral HPLC analysis.