Table 1.
Screening Catalysts and Conventional Lewis Acids.[a]
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Entry | Catalyst | Loading (mol%) | Time (h) | Yield (%)/[b] (α:β)[b] |
1 | Pd(CH3CN)4(BF4)2 | 5 | 5 | NR |
2 | Pd(PhCN)2(OTf)2 | 5 | 1 | 86 (10:1) |
3 | Pd(PhCN)2(OTf)2 | 2 | 1 | 85 (10:1) |
4 | Ni(PhCN)4(OTf)2 | 2 | 0.25 | 84 (11:1) |
5 | Ni(4-F-PhCN)4(OTf)2 | 2 | 0.25 | 88 (10:1) |
6 | Ni(4-MeO-PhCN)4(OTf)2 | 2 | 0.25 | 90 (10:1) |
7 | Ni(dppe)(OTf)2 | 2 | 1 | 85 (30:1) |
8 | Ni(dppe)Cl2 | 2 | 6 | NR |
9 | Ni(dppp)(OTf)2 | 2 | 1.75 | 70 (8:1) |
10 | Ni(dppb)(OTf)2 | 2 | 1.25 | 49 (9:1) |
11 | Ni(PPh3)(OTf)2 | 2 | 1.25 | 61 (12:1) |
12 | Ni(OTf)2 | 2 | 0.25 | 57 (19:1) |
13 | AgOTf | 6 | 14 | 72 (5:1) |
14 | TMSOTf | 4 | 2 | 72 (8:1) |
15 | BF3OEt2 | 6 | 6 | 65 (4:1) |
The conversions were performed at 0.2 M in CH2Cl2 with 2 −5 mol% of Pd/Ni catalysts or Lewis acids.
Isolated Yield.
1H NMR ratio.