Substrate scope for (E)-alkenyloxindolesa.
| |||||
|---|---|---|---|---|---|
| Entry | R1 | R2 | Yieldb (%) | drc | eed (%) |
| 1 | CO2tBu | H | 95 (3aa) | >19 : 1 | 92 |
| 2 | CO2Me | H | 91 (3ba) | >19 : 1 | 85 |
| 3 | CO2Et | H | 90 (3ca) | >19 : 1 | 89 |
| 4 | CO2iPr | H | 92 (3da) | >19 : 1 | 89 |
| 5 | CO2Ph | H | 92 (3ea) | >19 : 1 | 86 |
| 6 | CO2Bn | H | 91 (3fa) | >19 : 1 | 91 |
| 7 | CO2tBu | 5 F | 93 (3ga) | >19 : 1 | 91 |
| 8 | CO2tBu | 5-Cl | 87 (3ha) | >19 : 1 | 91 |
| 9 | CO2tBu | 5-Br | 85 (3ia) | >19 : 1 | 91 |
| 10 | CO2tBu | 5-Me | 95 (3ja) | >19 : 1 | 88 |
| 11 | CO2tBu | 5-OMe | 91 (3ka) | >19 : 1 | 87 |
| 12 | CO2tBu | 6-CF3 | 88 (3la) | >19 : 1 | 95 |
| 13 | CO2tBu | 7-F | 81 (3ma) | >19 : 1 | 94 |
| 14 | CO2tBu | 5,6-F2 | 98 (3na) | >19 : 1 | 90 |
| 15e | CO2tBu | H | 80 (3oa) | >19 : 1 | 98 |
| 16e | COPh | H | 82 (3pa) | >19 : 1 | 88 |
a
Unless otherwise noted, all the reactions were carried out with 1 (0.10 mmol, PG = Cbz), 2a (0.20 mmol) and L3-PiEt2/Ni(BF4)2·6H2O (1 : 1, 10 mol%) in CH2Cl2 (1.0 mL) at 30 °C for 24 h.
b
Isolated yield of 3.
c
Determined by 1H NMR.
d
Determined by HPLC analysis on a chiral stationary phase.
e
PG = Boc. Boc = tert-butoxycarbonyl and Cbz = benzyloxycarbonyl.