Table 2.
Enantioselective syntheses of Spirooxindoles a
| |||
|---|---|---|---|
|
| |||
| Entry | R1 | Pdt (Y%)b | Drc (ee %)d |
| 1 | Ph | 5a (80) | 6:1:0.5:0.4 (99) |
| 2 | 4-Me-Ph | 5b (82) | 6:1:0.5:0.3 (99) |
| 3 | 3-OMePh | 5c (82) | 7:1:0.5:0.4 (98) |
| 4 | 2-OMe-Ph | 5d (84) | 5.5:1:0.5 (99) |
| 5 | 3-Cl-Ph | 5e (74) | 5.2:1:0.5:0.5 (99) |
| 6 | 4-NO2-Ph | 5f (80) | 3:1:0.5 (99) |
| 7 | 3-NO2-Ph | 5g (74) | 3:1:0.7:0.5 (99) |
| 8e | 2-furyl | 5h (80) | 6:1:0.5:0.3 (98) |
| 9e | Pr | 5i (54) | 6:1:0.7 (95) |
| 10f | Ph | 5j (90) | 3:1:0.8:0.2 (95) |
a
General reaction conditions: oxindole (0.1 mmol), dialdehyde 2 (50% in water, 0.3 mmol), and organocatalyst A (0.01 mmol) in DMF (0.5 mL) at 23°C.
b
Isolated combined yield.
c
The ee was determined by chiral-phase HPLC analysis of major diastereomer.
d
Determined by 1H NMR of crude product.
e
The reaction was performed for 3 days.
f
Oxindole is protected as NAc.