| Reference | Temperature (˚C) | catalyst | solvent | Yield (%) |
| 36 | 0 | NaOH | H2O/Et2O | 75 |
| 37 | 25 | Lewis acid Y-Zr | MeCN | 90 |
| 38 | 25 | Zn | Benzene | 97 |
| 40 | 25 | Et3N | THF | 43 |
| 41 | 10 - 15 | NaOH | H2O | 97 |
| 42 | Reflux/IR | NaHCO3 | Acetone | 67.84 |