Table 1.
Entry | Catalyst | Amount | Yield (%) b,c |
---|---|---|---|
1 | CuI | 1.0 mol % | 43 |
2 | CuI | 2.0 mol % | 71 |
3 | CuI | 3.0 mol % | 90 |
4 | CuI | 4.0 mol % | 90 |
5 | CuBr | 3.0 mol % | 56 |
6 | CuCl | 3.0 mol % | 67 |
7 | CuCl2 | 3.0 mol % | 72 |
8 | Cu(OAc)2 | 3.0 mol % | 46 |
9 | CuO | 3.0 mol % | 61 |
10 | nano-CuO | 3.0 mol % | 65 |
11 | I2 | 3.0 mol % | 69 |
12 | - | - | Traces |
a Reaction conditions: 1a (0.25 mmol), 2a (2.0 equiv.), DMSO (3.0 equiv.) under MW irradiation; b Isolated yield; c This reaction works similarly in 0.125 mmol scale with less reproducibility.