Table 1.
Comparative activation of armed (1) and superarmed (2) glycosyl donors
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Entry | D | P | Temp. | Time | CP | Yield | α:β |
1 | 1A | DMTST | 0 °C | 2 h | 4 | 92% | 2:1 |
2 | 2A | DMTST | 0 °C | 5 min | 5 | 86% | β only |
3 | 1A | Cu(OTf)2 | 0 °C | 2 h | 4 | 99% | 2:1 |
4 | 2A | Cu(OTf)2 | 0 °C | 20 min | 5 | 96% | β only |
5 | 1B | IDCP | −10 °C | 20 h | 4 | 62% | 3:1 |
6 | 2B | IDCP | −10 °C | 3 h | 5 | 53% | β only |
7 | 1C | IDCP | −10 °C | 96 h | 4 | 82% | 2:1 |
8 | 2C | IDCP | −10 °C | 96 h | 5 | 78% | β only |
9 | 1C | MeOTf | 0 °C | 18 h | 4 | 95% | 2:1 |
10 | 2C | MeOTf | 0 °C | 6 h | 5 | 96% | β only |
11 | 1C | DMTST | −20 °C | 1 h | 4 | 90% | 2:1 |
12 | 2C | DMTST | −20 °C | 10 min | 5 | 89% | β only |