Table 4.
One-pot, regioselective protection of sugar polyols with silyl and alkyl groupsa.
| Entry | Substrate | First step conditions (equiv) | Second step conditions (equiv) | Product, isolated yield |
| 1 | 1 | DIPEA (2.5), Bu2SnO (0.1), TBAB (0.3), BnBr (4), 70 °C, 3.5 h | pyridine (2.2), TBDMSCl (2.0), rt, 3 h | low silylation yields |
| 2 | 1 | DIPEA (2.5), Bu2SnO (0.1), TBAB (0.3), BnBr (4), 70 °C, 3.5 h | pyridine (5.0), TBDMSCl (2.0), rt, 3 h |
 29, 61% |
| 3 | 1 | pyridine (2.2), TBDMSCl (1.1), TBAB (0.3), rt, 1.5 h | DIPEA (3.5), Bu2SnO (0.1), BnBr (5.5), 70 °C, 4.5 h | 29, 39% |
| 4 | 1 | DIPEA (4), Bu2SnO (0.1), TBAB (0.3), AllBr (8), 90 °C, 3.5 h | pyridine (5.0), TBDPSCl (1.5), rt, 3.5 h |
 30, 59% |
| 5 | 1 | pyridine (3.0), TBDPSCl (1.1), TBAB (0.3), rt, 3 h | DIPEA (2.5), Bu2SnO (0.1), BnBr (6), 80 °C, 4 h |
 31, 62% |
| 6 | 3 | pyridine (3.0), TBDPSCl (1.1), TBAB (0.3), rt, 3 h | DIPEA (2.5), Bu2SnO (0.2), BnBr (7), 90 °C, 4 h |
 32, 42% |
| 7 | 8 | DIPEA (2.5), Bu2SnO (0.1), BnBr (2), TBAB (0.3) 70 °C, 2.5 h | pyridine (3.5), TBDMSCl (2.0), TBAB (0.3), rt, 1 h |
 33, 69% |
| 8 | 8 | DIPEA (2.5), Bu2SnO (0.1), BnBr (2), TBAB (0.3), 70 °C, 2.5 h | pyridine (3.5), TBDPSCl (1.5), rt, 2.5 h |
 34, 75% |
| 9 | 5 | DIPEA (2.5), Bu2SnO (0.1), BnBr (4), TBAB (0.3), 70 °C, 2 h | pyridine (6), TBDMSCl (2), rt, 1.5 h |
 35, 57% |
aGeneral conditions: upon completion of the first step (see times in pertinent entries), the temperature was modified according to conditions of the second step, and the requisite reagents added.