Table 5.
Synthetic Protocol B (For more details see Supporting Information).
| Procedure | Reagents | Volume/Time |
|---|---|---|
| H-Phosphonate/H-Phosphinate Condensation Step | ||
| Deblocking | 3% DCA in DCM | Flow through the column 6 mL/2 min |
| DCA washout | 5% pyridine in methanol | |
| Condensation | 0.1M monomer in ACN/Py (1:1) | 120 µL/10 min |
| 0.3M DMOCP in ACN/Py (95:5) | ||
| Oxidation or Sulfurization | Ox-C or Ox-E | 220 µL/30 min |
| Capping | Ac2O/Py/THF (1:1:1:17) | 2 × 150 µL/3 min |
| MeIm/THF (1:9) | ||
| Phosphoramidite Condensation Step | ||
| Deblocking | 3% DCA in DCM | Flow through the column 6 mL/2 min |
| DCA washout | 5% pyridine in methanol | |
| Condensation | 0.1M monomer in ACN | 120 µL/5 min |
| 0.25M ETT in ACN | ||
| Oxidation or Sulfurization | CSO, tBuOOH or DDTT | 220 µL/3.5 min |
| End of Synthetic Cycle | ||
| S-cyanoethyl-ester cleavage * | 1M DBU in ACN | 220 µL/3 min |
| Cleavage from solid support | Ammonia gas at 0.7 MPa | Gas chamber/16 h |
* Applicable only in case of CSS sulfurization mixtures.