Table 2. Optimization of the Pd Coupling Reaction of 65 with 66 (X = SnBu3) or 67 (X = H)a.
| entry | reaction conditions | X | result |
|---|---|---|---|
| 1 | Pd(PPh3)4, LiCl, CuCl | SnBu3 | decomposition |
| 2 | Pd2dba3, P(furyl)3, 50 °C | SnBu3 | decomposition |
| 3 | Pd(OAc)2, KOAc, 80 °C | H | dimerization |
| 4 | PdCl2(MeCN)2, DMF, heat | SnBu3 | decomposition |
| 5 | PdCl2(PPh3)2, toluene, heat | SnBu3 | decomposition |
| 6 | CuTC, NMP | SnBu3 | ca. 5% desired product |
| 7 | Pd(PPh3)4, CuTC, [Ph2PO2][NBu4] |
SnBu3 | 55% desired product |
a
Compound 65 was used without further purification from the previous step.