Table 1.
Comparison of reaction yields of allylglycoside formation using varying procedures or conditions
| Entry | Glycosyl Donor (conc.: 0.128M in CH2Cl2) |
Lewis Acid (2 equiv.) |
Allyl Alcohol [equiv.] |
Reacetylation | Peracetylated allyl glycosidea |
Yield (isolated) |
|---|---|---|---|---|---|---|
| 1 | 7 | BF3·Et2O | 1.1 | yes | 11 ( : = 1:12) | 20% |
| 2 | 7 | TMSOTf | 4 | no | 11 ( : = 1:6) | 20% |
| 3 | 7 | TMSOTf | 4 | yes | 11 ( : = 1:13) | 68% |
| 4 | 8 | BF3·Et2O | 1.1 | yes | 12 ( : = 1:12) | 36% |
| 5 | 8 | BF3·Et2O | 4 | no | 12 ( : = 1:10) | 22% |
| 6 | 8 | BF3·Et2O | 4 | yes | 12 ( : = 1:12) | 61% |
| 7 | 9 | BF3·Et2O | 1.1 | yes | 13 ( : = 1:25) | 39% |
| 8 | 9 | BF3·Et2O | 4 | no | 13 ( only) | 24% |
| 9 | 9 | BF3·Et2O | 4 | yes | 13 ( : = 1:2) | 76% |
| 10 | 10 | BF3·Et2O | 1.1 | no | 14 ( : = 1:3) | 22% |
| 11 | 10 | BF3·Et2O | 4 | no | 14 ( only) | 18% |
| 12 | 10 | BF3·Et2O | 4 | yes | 14 ( : = 1:3) | 70% |
a
The ratio of and anomers was determined by 1H NMR spectroscopy.