Table 1 Screening and optimization of the reaction conditions[a]
From: Photosensitizer-free visible-light-promoted glycosylation enabled by 2-glycosyloxy tropone donors
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|---|---|---|
Entry | Conditions | Yield (%)[a] |
1 | No light, 3 h | 3a (0) |
2 | 310-320 nm, 3 h | 3a (22) |
3 | 365-370 nm, 3 h | 3a (20) |
4 | 385-390 nm, 3 h | 3a (65) |
5 | 415-420 nm, 3 h | 3a (66) |
6 | 430-435 nm, 3 h | 3a (65) |
7 | blue LEDs, 3 h | 3a (67) |
8 | blue LEDs (10 W), 3 h | 3a (59) |
9 | blue LEDs (5 W), 3 h | 3a (20) |
10 | blue LEDs (3 W), 3 h | 3a (10) |
11[b] | blue LEDs, 5 h | 3a (82) |
12[c] | blue LEDs, NaOTf, 20 min | 3a (91) |
13[d] | NaOTf, 2.5 h | 3b (71) |
14[d] | NaB(3,5- (CF3)2Ph)4, 6 h | 3b (63) |
15[d] | NaSO2CF3, 2.5 h | 3b (60) |
16[d] | NaBF4, 12 h | 3b (30) |
17[d] | NaNTf2, 8 h | 3b (41) |
18[d] | NaSO4Me, 2 h | 3b (50) |
19[d] | Bu4NOTf, 8 h | 3b (42) |
20[d] | KOTf, 8 h | 3b (54) |
21[d] | TMSOTf, 0.5 h | 3b (92) |
22[d] | TMSOTf, in the dark, 12 h | 3b (44) |
23[d] | NaOTf, in the dark, 12 h | 3b (0) |
24[d] | no additive, 12 h | 3b (13) |
25[d] | no additive, no light, 24 h | 3b (0) |
