Table 1.
Entry | Conditions | 3a (%)a | Entry | Conditions | 3a (%)a |
---|---|---|---|---|---|
1 | Ni(COD)2, KOtBu, PhMe, 110 °C, 24 h | 56 | 7 | Ni(COD)2, KOMe, c-hexane/THF 1/2 | 60 |
2 | Ni(COD)2, KOtBu, other solvents (e.g., c-hexane) | ≤74 | 8 | Ni(COD)2, KHMDS, c-hexane/THF 1/2 | 56 |
3 | Ni(COD)2, KOtBu, c-hexane/THF 4/1 | 74 | 9 | Ni(PPh3)2Cl2, KOtBu, c-hexane/THF 1/2 | 20 |
4b | Ni(COD)2, KOtBu, c-hexane/THF 1/2 | 89 | 10 | Ni(acac)2, KOtBu, c-hexane/THF 1/2 | 12 |
5 | Ni(COD)2, KOtBu, c-hexane/THF 1/4 | 59 | 11b | none metal catalyst, KOtBu, c-hexane/THF 1/2 | 0 |
6 | Ni(COD)2, NaOtBu, c-hexane/THF 1/2 | 71 | 12b | Ni(COD)2, none base, c-hexane/THF 1/2 | 0 |
Reaction conducted on 0.2 mmol scale, 80 °C, 24 h
aYield by gas chromatography. The reaction conditions (entry 4) are optimal
brt, 2 h