Entry | Mole ratio of 1a/2 | Solvent | Temp (˚C) | Time (h) | Yield (%) |
1 | 1:1 | CH3CN | r.t | 6 | 30 |
2 | 1:1.5 | CH3CN | r.t | 6 | 50 |
3 | 1:2 | CH3CN | r.t | 6 | 80 |
4 | 1:2 | CH3CN | Reflux | 6 | 60 |
5 | 1:2 | CH3CN | 0 | 6 | 70 |
6 | 1:2 | CH3CN | rt | 24 | 97 |
7 | 1:2 | THF | rt | 6 | 20 |
8 | 1:2 | CH2Cl2 | rt | 6 | 40 |
9 | 1:2 | Toluene | rt | 6 | 0 |
10 | 1:2 | CH2Cl2/Toluene | rt | 6 | 30 |