Table 1.
Optimization of the reaction conditionsa
| Entry | Electrodes | Linkage | Light source | Current | Electrolyte | Solvent | Yield (%) / 1b | Yield (%) / 41b |
|---|---|---|---|---|---|---|---|---|
| 1 | (+)GF/(-)GF | w/o | 20 W 395-400 nm | 4 mA | Bu4NBF4 | MeCN | 48 | - |
| 2 | (+)GF/(-)GF | w/o | 20 W 395-400 nm | 4 mA | Et4NCl | MeCN | 57 | - |
| 3 | (+)GF/(-)GF | w/o | 20 W 395-400 nm | 4 mA | LiCl | MeCN | 91 | - |
| 4 | (+)GF/(-)GF | w/o | 30 W 395-400 nm | 4 mA | LiCl | MeCN | 79 | - |
| 5 | (+)GF/(-)GF | w/o | 10 W 395-400 nm | 4 mA | LiCl | MeCN | 17 | - |
| 6c | (+)GF/(-)GF | w/o | 20 W 395-400 nm | 4 mA | LiCl | MeCN | n.d. | - |
| 7 | (+)GF/(-)Pt | w/o | 20 W 395-400 nm | 4 mA | LiCl | MeCN | 69 | - |
| 8 | (+)C-rod/(-)GF | w/o | 20 W 395-400 nm | 4 mA | LiCl | MeCN | 27 | - |
| 9 | (+)GF/(-)GF | w/o | 20 W 395-400 nm | 10 mA | LiCl | MeCN | 56 | - |
| 10 | (+)GF/(-)GF | w | 20 W 395-400 nm | 4 mA | LiCl | MeCN | 41 | 22 |
| 11d | (+)GF/(-)GF | w | 20 W 395-400 nm | 25 mA | LiCl | MeCN | 11 | 59 |
| 12d | (+)GF/(-)GF | w | 20 W 393 nm | 25 mA | LiCl | MeCN | 7 | 82 |
| 13d | (+)GF/(-)GF | w | 20 W 393 nm | 25 mA | LiCl | MeCN/Acetone | trace | 93 |
| 14d,e | (+)GF/(-)GF | w | 20 W 393 nm | 25 mA | LiCl | MeCN/Acetone | n.d. | n.d. |
| 15e | (+)GF/(-)GF | w/o | 20 W 395-400 nm | 4 mA | LiCl | MeCN | n.d. | n.d. |
aReaction conditions: 1a (3 mmol), 2a (0.3 mmol), 3a (0.6 mmol), FeCl3·6H2O (10 mol%), NiBr2·3H2O (10 mol%), 2,2’-bipyridine (10 mol%), LiCl (2.0 equiv.), dry MeCN (6.0 mL), 4 mA, 12 h, 20 W 395-400 nm, argon, graphite felt (GF) as electrodes, undivided cell. bGC yields using biphenyl as an internal standard. cCeCl3 instead of FeCl3·6H2O. d4,4’-di-tert-butyl-2,2’-bipyridine was used as ligand. ew/o paired catalyst or light or electricity. n.d. not detected, w/o without, w with.