Table 3.
Screening of Chiral Phase-Transfer Catalysts.
| entry | catalyst | additive | conv. (%)b | 9La/6L; 9La/10Lab | ee of 9La (%)c |
|---|---|---|---|---|---|
| 1 | C-1 | -- | 83 | 9/91; 25/75 | -- |
| 2 | C-1 | A-1 (100) | 100 | 30/70; 87/13 | 98 (S, R) |
| 3 | C-1 | A-2 (100) | 87 | 58/42; 89/11 | >99 (S, R) |
| 4 | QD-1 | A-2 (100) | 100 | 79/21; 81/19 | >99 (S, R) |
| 5 | QD-1 | A-2 (50) | 100 | 90/10; 82/18 | >99 (S, R) |
| 6d | QD-1 | A-2 (50) | 100 | 90/10; 82/18 | >99 (S, R) |
| 7d | Q-1 | A-2 (50) | 100 | 82/18; 78/22 | 99 (R, S) |
| 8d | epiQ-1 | A-2 (50) | 100 | 90/10; 84/16 | >99 (R, S) |
a
Unless noted, reactions were performed with 1L (0.025 mmol), 8a (0.05 mmol), additive (y mol %), aqueous KOH solution (0.22 μL, 50 wt %, 10 mol %) in PhMe (0.25 mL) with catalyst (x mol %) at −30 °C.
b
Determined by 19F NMR analysis.
c
Determined by HPLC analysis.
d
0.5 mol % catalyst was used.