Table 1 Reaction optimization.
Reaction conditions: 1a (0.20 mmol), 2 (0.30 mmol), base (3.0 equiv), solvent (1.0 ml), 24 hours, under Ar. CCDC, Cambridge Crystallographic Data Centre.
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| 1 | X | [Rh] (mol %) | Base | Solvent | T (°C) | Yield (%)* |
| 1 | Br (2a) | Rh(PPh3)3Cl (6.0) | Cs2CO3 | Toluene | 110 | 10 |
| 2 | Br (2a) | Rh(PPh3)3Cl (6.0) | tBuONa | Toluene | 110 | 33 |
| 3 | Br (2a) | Rh(PPh3)3Cl (6.0) | tBuOLi | Toluene | 110 | 84 |
| 4 | Br (2a) | Rh(PPh3)3Cl (6.0) | tBuOLi | PhCl | 110 | 89 |
| 5 | Br (2a) | Rh(PPh3)3Cl (6.0) | tBuOLi | PhCF3 | 110 | 91 |
| 6 | Br (2a) | Rh(PPh3)3Cl (6.0) | tBuOLi | m-Xylene | 110 | 94 |
| 7 | Br (2a) | Rh(PPh3)3Cl (6.0) | tBuOLi | m-Xylene | 80 | 96 |
| 8 | Br (2a) | Rh(PPh3)3Cl (6.0) | tBuOLi | m-Xylene | 60 | 15 |
| 9 | Cl (2a′) | Rh(PPh3)3Cl (6.0) | tBuOLi | m-Xylene | 110 | 84 |
| 10 | I (2a″) | Rh(PPh3)3Cl (6.0) | tBuOLi | m-Xylene | 110 | Trace |
| 11 | Br (2a) | Rh(PPh3)3Cl (3.0) | tBuOLi | m-Xylene | 80 | 81 |
| 12 | Br (2a) | Rh(PPh3)3Cl (1.0) | tBuOLi | m-Xylene | 80 | 64 |
| 13 | Br (2a) | [Rh(cod)Cl]2 (3.0) | tBuOLi | m-Xylene | 80 | 11 |
| 14† | Br (2a) | [Rh(cod)Cl]2 (3.0) | tBuOLi | m-Xylene | 80 | 64 |
| 15 | Br (2a) | – | tBuOLi | m-Xylene | 80 | 0 |
*Isolated yields.
†With 10 mol % PPh3.