Table 1 Optimization of reaction conditionsa
From: Divergent synthesis of chiral cyclic azides via asymmetric cycloaddition reactions of vinyl azides
| |||||
|---|---|---|---|---|---|
Entry | Metal | Ligand | endo/exob | Yield (%)c | ee (%)d |
1 | Sc(OTf)3 | – | – | 30 | – |
2 | InCl3 | – | 80/20 | 83 | – |
3 | Cu(OTf)2 | – | 60/40 | 62 | – |
4 | Cu(OTf)2 | L1 | 50/50 | 50 | 94 |
5 | Cu(OTf)2 | L2 | 10/90 | 17 | 41 |
6 | Cu(OTf)2 | L3 | 60/40 | 25 | 98 |
7 | Cu(OTf)2 | L4 | 80/20 | 40 | 96 |
8 | Cu(OTf)2 | L5 | – | 0 | – |
9 | Cu(OTf)2 | L6 | – | 0 | – |
10 | Cu(SbF6)2 | L3 | 60/40 | 86 | 96 |
11 | Cu(ClO4)2·6H2O | L3 | – | 0 | – |
12 | Cu(SbF6)2 | L7 | 60/40 | 83 | 37 |
13 | Cu(SbF6)2 | L8 | 60/40 | 99 | 96 |
14 | Cu(SbF6)2 | L9 | 80/20 | 89 | >99 |
