Table 2.
The activation of glycosyl sulfoxide using different LaIII salts.
| No. | Ln[OTf]3 (equiv) | Activator | Solvent | Temp [°C] | Time | Yield [%] | α/β |
|---|---|---|---|---|---|---|---|
| 1 | Yb (1) | Tf2O | CH2Cl2 | −78→RT | 10 h | 63 | 1:2 |
| 2 | Yb (1) | Tf2O | CH3CN | −40→RT | 12 h | 63 | 1:2.8 |
| 3 | Yb (1) | NIS | CH2Cl2 | RT | 20 min | 47 | 1:1.5 |
| 4 | Yb (1) | NIS–TfOH (cat.) | CH2Cl2 | −78 | 8.5 h | 59 | 1:2.9 |
| 5 | Eu (1) | Tf2O | CH2Cl2 | −78→RT | 10 h | 76 | 1:1.5 |
| 6 | Eu (1) | Tf2O | CH3CN | −40→RT | 10 h | 82 | 1:4.3 |
| 7 | Eu (1) | NIS | CH2Cl2 | RT | 20 min | 48 | 1:2 |
| 8 | Eu (1) | NIS–TfOH (cat.) | CH2Cl2 | −78 | 6 h | 64 | 1:3 |
| 9 | La (1) | Tf2O | CH2Cl2 | −78→RT | 12 h | 51 | 1.7:1 |