Table 1. Optimization of Decarboxylative Cross-Coupling.
entry | X | ligand | temp (°C) | yield of 1aa,b (%) |
---|---|---|---|---|
1 | I | PCy3HBF4 | 140 | 58 |
2 | I | PtBu3HBF4 | 140 | 79 |
3 | I | none | 140 | 72 |
4c | I | PtBu3HBF4 | 140 | 0 |
5 | Br | none | 140 | 6 |
6 | Br | PCy3HBF4 | 140 | 32 |
7 | Br | PtBu3HBF4 | 140 | 13 |
8 | Br | CM-Phos | 140 | 55 |
9 | Br | CM-Phos | 160 | 62 |
10c | Br | CM-Phos | 160 | 0 |
11 | Cl | CM-Phos | 140 | 31 |
12 | Cl | PtBu3HBF4 | 140 | 0 |
13 | Cl | PCy3HBF4 | 140 | <2 |
14 | Cl | DPPF | 140 | 51 |
15c | Cl | DPPF | 140 | 0 |
General conditions: Ni(COD)2 (0.1 equiv), ligand (0.2 equiv), diglyme, 20 h.
Calibrated GC yields against hexadecane as the internal standard.
General conditions but with no Ni(COD)2.