Entry | Mole ratio of 1/2 | Halogen source | Solvent | Condition | Time | Yielda (%) |
1 | 1:4 | NCS | CH3CN | Air | 24 h | 80 |
2 | 1:2 | NBS | CH3CN | Air | 4 h | 94 |
3 | 1:0.67 | TCCA | CH3CN | N2 | 6 h | 90 |