Table 3:
Asymmetric synthesis of 1,5-benzothiazepine scaffold
| |||||
|---|---|---|---|---|---|
| Entry | Catalyst | T [°C]/Additive | t1(t2) [h] | Yield [%]a | ee [%]b |
| 1 | I | rt | 92 | 85 | 52 |
| 2 | I | 40 °C | 14(11) | 81 | 66 |
| 3 | I | rt/silica gel | 1.5(4) | 82 | 76 |
| 4 | - | rt | 72 | 30 | - |
| 5 | - | rt/silica gel | 5 | 85 | - |
| 6 | II | rt/silica gel | 1.5(4) | 85 | −61 |
| 7 | III | rt/silica gel | 1.5(4) | 81 | −61 |
| 8 | IV | rt/silica gel | 2(4) | 80 | −81 |
| 9 | V | rt/silica gel | 2.5(4) | 75 | −76 |
| 10 | VI | rt/silica gel | 14(4) | 95 | −64 |
| 11 | VII | rt/silica gel | 0.5(4) | 97 | −80 |
| 12 | VIII | rt/silica gel | 4.5(4) | 71 | 66 |
Determined by 1H NMR spectroscopy using 1,3,5-(MeO)3C6H3 as an internal standard.
Determined by HPLC on a chiral stationary phase. Negative sign indicates the enantiomeric excess (ee) for the opposite enantiomer.