2. Optimizing the Reaction Conditions .
| Entry | L1 (mol %) | Time (h) | Conv. (%) | ee (%) | TON |
|---|---|---|---|---|---|
| 1 | 2 | 4 | >99 | 90 | - |
| 2 | 1 | 4 | >99 | 90 | - |
| 3 | 0.1 | 6 | >99 | 90 | - |
| 4 | 0.1 | 24 | 99 (98) | 92 | - |
| 5 | 0.01 | 12 | >99 | 90 | - |
| 6 | 0.005 | 24 | 99 (97) | 90 | 19,400 |
| 7 | 0.002 | 48 | 99 (93) | 80 | 46,500 |
| 8 | 0.001 | 48 | 50 | 79 | - |
| 9 | - | 24 | 22 | rac. |
a
Reaction conditions: 1a (0.1–200 mmol), (S, S, S)-L1 (0.002 mmol), Zn(OAc)2 (0.006 mmol), THF (1–270 mL), r.t.
b
The conversion of 1a was determined by GC using n-decane as the internal standard.
c
The ee values of 2a were determined by chiral HPLC.
d
0 °C.
e
Isolated yield in parentheses.
f
Zn(OAc)2 (0.015 mol %), without a chiral ligand.