Table 2. Optimization of the Catalyst.
entry | catalyst | NMR yield, % | 5a:6a |
---|---|---|---|
1 | Ph3PAuCl/AgSbF6 | >99 | 50:50 |
2 | Ph3PAuCl/AgOTf | 85 | 82:18 |
3 | (ArO)3PAuCla/AgOTfb,c | 81d | 96:4e |
4 | (ArO)3PAuCla/AgSbF6b | 76 | 22:78 |
5 | IPrAuCl/AgOTf | 79 | 33:67 |
6 | IPrAuCl/AgSbF6 | 81 | 0:100 |
7 | AgOTfb | 39 | 87:13 |
8 | AgSbF6 | 39 | 86:14 |
Ar = 2,4-di-tBuPh.
Solution [0.04M].
T = −30 °C.
76% NMR yield at rt.
Ratio of 91:9 at rt.