Table 1.
Synthesis of 2b under different reaction conditions.
| Entry | Solvent | Ratio a | Time (h) | Reaction temperature | Yield (%) b |
|---|---|---|---|---|---|
| 1 | DMF | 1:3:3 | 16 | r.t | 11.2 |
| 2 | acetone | 1:3:3 | 16 | r.t | 19.0 |
| 3 | CH3CN | 1:3:3 | 16 | r.t | 34.9 |
| 4 | THF | 1:3:3 | 16 | r.t | 55.0 |
| 5 | THF | 1:3:1 | 16 | r.t | 12.0 |
| 6 | THF | 1:3:2 | 16 | r.t | 20.0 |
| 7 | THF | 1:1:1 | 16 | r.t | 0 |
| 8 | THF | 1:3:4 | 16 | r.t | 49.5 |
| 9 | THF | 1:3:3 | 4 | r.t | 0 |
| 10 | THF | 1:3:3 | 8 | r.t | 23.0 |
| 11 | THF | 1:3:3 | 20 | r.t | 56.0 |
| 12 | THF | 1:3:3 | 16 | 0-5°C | 23.0 |
| 13 | THF | 1:3:3 | 16 | 40-45°C | 13.0 |
a Ratio of 2-cyano-3,3-dimethylthioacrylate:O,O’-di-i-propylphosphite:sodium hydride
b Isolated yield based on 2-cyano-3,3-dimethylthioacrylate