Table 1.
entry | ligand | solvent | temp (°C) | time (min) | % yield (dr) |
---|---|---|---|---|---|
1 | dppe | THF | 60 | 30 | 42 |
2 | PCy3 | THF | 60 | 30 | 20 |
3 | P(t-Bu)3 | THF | 25 | 10 | 35 |
4 | none | THF | 0 | 10 | 64 (4.8:1) |
5 | none | dioxane | 90 | 30 | 54 (3.5:1) |
6 | none | toluene | 60 | 5 | 45 (>19:1) |
7 | none | THF | 25 | 5 | 72 (5.3:1) |
8 | none | THF | 60 | 5 | 68 (>19:1) |
Entries 1-4: 1a (1.0 equiv) was added to a premixed solution of TMSCHN2 (2.0 equiv) and Ni(COD)2 (10 mol %). Entries 5-8: Ni(COD)2 (10 mol %) was added to a premixed solution of 1a (1.0 equiv) and TMSCHN2 (2.0 equiv).