Table 4.
Entry | Azolium salt | Yieldb (%) of 22 + 23 | ee (%) of 22 |
---|---|---|---|
1 | 15 | 51 | 33 |
2 | 16 | –c | 9d |
3 | 17 | –c | 23d |
4 | 18 | 58 | 55 |
5 | 19 | 45 | 59 |
6 | 20 | 0 | – |
7 | 21 | 0 | – |
Reaction conditions: 15–21 (0.02 mmol), DIPEA (0.05 mmol), 14 (0.20 mmol), EtOH (0.41 mmol), THF (1.0 mL), r.t., 12–24 h.
Isolated yields.
Not isolated.
Assessed by HPLC of crude reaction mixture.