Table 2. Competitive Donor Activations.
entry | donor I | donor II | productsa | yieldb (%) |
---|---|---|---|---|
1 | 1 | 2 | 1C/2C, 14:1 | 65 |
2 | 1 | 3 | 1C/3C, 1:0 | 80 |
3 | 2 | 3 | 2C/3C, 6:1 | 37 |
4 | 3 | 4 | 3C/4C, 1.6:1 | 39 |
5c | 4 | 5 | 4C/5C, 1:0 | 64 |
Determined by 1H NMR spectroscopy of the isolated disaccharide.
The disaccharide fraction was quantified after isolation by size-exclusion chromatography and related to the limiting amount of NIS (see Experimental Section).
The combined donor concentration was 0.1 M, triflic acid was added at −20 °C, the reaction mixture was heated to +15 °C overnight, and then the reaction was quenched (Et3N).