Table 1. The effect of a 3-O-acyl protection on the stereoselectivity of mannosylation.
| ||||
| Entry | Donor (EWG) | Acceptor (1.0 equiv.) | Disaccharide yield | α/β ratio |
| 1 | 24 (Ac) | 27 | 91% | 1/25.9 |
| 2 | 24 (Ac) | 28 | 94% | 1/39.0 |
| 3 | 24 (Ac) | 29 | 92% | 1/40.4 |
| 4 | 25 (Bz) | 28 | 88% | 1/29.6 |
| 5 | 26 (SO2Bn) | 27 | 95% | 15.9/1 |
| 6 | 26 (SO2Bn) | 28 | 93% | 10.2/1 |