Table 1.
Entry | Deviation from standard conditions | Yield of 3a (%) (ax:eq) |
---|---|---|
1 | - | 84 (3.6:1) |
2 | L1 instead of dtbbpy | 0 |
3 | L2 instead of dtbbpy | 10 (2.9:1) |
4 | L3 instead of dtbbpy | <1 |
5 | Without i-PrOH | 63 (3.5:1) |
6 | 1,4-Dioxane as solvent | 40 (3.4:1) |
7 | Ni(cod)2 instead of NiBr2·DME | 35 (3.8:1) |
8 | DIPEA instead of CS2CO3 | 0 |
9 | Room temp instead of 80 °C | <1 |
10 | With air | 0 |
See Supporting Information (SI) for experimental details. Yields of 3a and axial:equatorial (ax:eq) ratios were determined by 1H-NMR using dibromomethane as the internal standard.