Screening experiments for desulfurization of zwitterion 23aa.
| ||||||
|---|---|---|---|---|---|---|
| Entry | Catalyst (mol%) | Solvent | Temp | Time | Product | Yield (%) |
| 1 | Pd/C (10% mol) | EtOH | rt | 16 h | 29 | Traces |
| 2 | Pd/C (10% mol) | EtOH | Reflux | 16 h | 29 | Traces |
| 3 | Pd/C (10% mol) | EtOH | Reflux | 4 h | 29 : 30 : 31 | 38 : 40 : 13 |
| 4 | RANEY®-Ni | THF : H2O (8 : 2) | rt | 8 h | 29 | 6 |
| 5 | RANEY®-Ni | Acetone | rt | 14 h | 29 | 19 |
| 6 | RANEY®-Ni | EtOH | −10 °C to rt | 8 h | 29 | 13 |
| 7 | RANEY®-Ni | Toluene | Reflux | 8 h | 31 | 38 |
| 8 | Zn (15 equiv.) | AcOH | rt | 7 days | 29 | 98 |
a
Ammonium formate was used as a hydrogen source.