Reaction optimizationa.
| ||
|---|---|---|
| Entry | Variations from standard conditions | Yieldb |
| 1 | None | 84% |
| 2 | ROCOCO2Li | 55% |
| 3 | ROCOCO2Na | 71% |
| 4 | ROCOCO2K | 62% |
| 5 | NiCl2·DME | 70% |
| 6 | NiCl2·(PPh3)2 | 63% |
| 7 | NiBr2·dtbbpy | 52% |
| 8 | NiI2 | 40% |
| 9 | Ni(COD)2 | 34% |
| 10 | w/o photocatalyst | 0 |
| 11 | w/o nickel catalyst | 0 |
| 12 | w/o visible light | 0 |
| 13 | w/o ligand | 27% |
| 14 | w/o bis(4-methoxyphenyl)methanone | 78% |
a
Reaction conditions: Ir-1 (2 mol%), NiCl2(Py)4 (20 mol%), dtbbpy (20 mol%), alkene 2 (0.1 mmol), bromide 3 (2.0 equiv.), oxalate 1 (3.0 equiv.), bis(4-methoxyphenyl)methanone (additive) (10 mol%), DMSO [0.05 M], 37 °C, 90W blue LED.
b
Yields were determined by 1H NMR analysis of the crude reaction mixtures.